Devices and methods for percutaneous surgery

ABSTRACT

Methods and devices for performing surgery in a patient are provided. A cannula provides a working channel for access to a location in the patient. A clamp assembly is removably engaged to the cannula. The clamp assembly allows use of an endoscopic viewing system or can be removed to allow use of a microscopic viewing system in order to view the surgical site in the patient through the working channel. The clamp assembly includes a viewing element mounting portion having a length along which an endoscopic viewing element can be selectively positioned.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation-in-part of U.S. patentapplication Ser. No. 09/815,693 filed on Mar. 23, 2001, and issuing asU.S. Pat. No. 6,679,833; which is a continuation-in-part ofInternational Patent Application Number PCT/US99/21866, filed on Sep.21, 1999, and having a priority date of Sep. 25, 1998, which is herebyincorporated by reference. Also, the present application is acontinuation-in-part of U.S. patent application Ser. No. 09/815,693filed on Mar. 23, 2001 and issuing as U.S. Pat. No. 6,679,833; which isa continuation-in-part of U.S. patent application Ser. No. 09/233,879filed on Jan. 20, 1999 and now issued as U.S. Pat. No. 6,217,509; whichis a divisional of U.S. patent application Ser. No. 08/736,626, filed onOct. 24, 1996, now issued as U.S. Pat. No. 5,902,231; which is acontinuation-in-part of U.S. patent application Ser. No. 08/620,933,file Mar. 22, 1996, and now issued as U.S. Pat. No. 5,792,044. Also,this application is a continuation-in-part of U.S. patent applicationSer. No. 10/359,996 filed on Feb. 6, 2003; which is a continuation ofU.S. patent application Ser. No. 09/449,647 filed Nov. 30, 1999, nowissued as U.S. Pat. No. 6,520,907; which is a divisional application ofU.S. patent application Ser. No. 08/920,991, filed Aug. 29, 1997, andnow issued as U.S. Pat. No. 6,007,487; which is a divisional of U.S.application Ser. No. 08/620,933, filed on Mar. 22, 1996, now issued asU.S. Pat. No. 5,792,044.

BACKGROUND

The present invention relates to devices, instruments and methods forperforming percutaneous surgeries, particularly at locations deep withinthe body. One specific application of the invention concern devices,instruments and techniques for percutaneous, minimally invasive spinalsurgery. In another aspect of the invention, the percutaneous surgery isperformed under direct vision at any location in the body.

Traditional surgical procedures for pathologies located deep within thebody can cause significant trauma to the intervening tissues. These openprocedures often require a long incision, extensive muscle stripping,prolonged retraction of tissues, denervation and devascularization oftissue. Most of these surgeries require recovery room time of severalhours and several weeks of post-operative recovery time due to the useof general anesthesia and the destruction of tissue during the surgicalprocedure. In some cases, these invasive procedures lead to permanentscarring and pain that can be more severe than the pain leading to thesurgical intervention.

Minimally invasive alternatives such as arthroscopic techniques reducepain, post-operative recovery time and the destruction of healthytissue. Orthopedic surgical patients have particularly benefited fromminimally invasive surgical techniques. The site of pathology isaccessed through portals rather than through a significant incision thuspreserving the integrity of the intervening tissues. These minimallyinvasive techniques also often require only local anesthesia. Theavoidance of general anesthesia reduces post-operative recovery time andthe risk of complications.

Minimally invasive surgical techniques are particularly desirable forspinal and neurosurgical applications because of the need for access tolocations deep within the body and the danger of damage to vitalintervening tissues. For example, a common open procedure for discherniation, laminectomy followed by discectomy requires stripping ordissection of the major muscles of the back to expose the spine. In aposterior approach, tissue including spinal nerves and blood vesselsaround the dural sac, ligaments and muscle must be retracted to clear achannel from the skin to the disc. These procedures normally take atleast one-two hours to perform under general anesthesia and requirepost-operative recovery periods of at least several weeks. In additionto the long recovery time, the destruction of tissue is a majordisadvantage of open spinal procedures. This aspect of open proceduresis even more invasive when the discectomy is accompanied by fusion ofthe adjacent vertebrae. Many patients are reluctant to seek surgery as asolution to pain caused by herniated discs and other spinal conditionsbecause of the severe pain sometimes associated with the muscledissection.

In order to reduce the post-operative recovery time and pain associatedwith spinal and other procedures, micro-surgical techniques have beendeveloped. For example, in micro-surgical discectomies, the disc isaccessed by cutting a channel from the surface of the patient's back tothe disc through a small incision. An operating microscope or loupe isused to visualize the surgical field. Small diameter micro-surgicalinstruments are passed through the small incision and between twolaminae and into the disc. The intervening tissues are disrupted lessbecause the incision is smaller. Although these micro-surgicalprocedures are less invasive, they still involve some of the samecomplications associated with open procedures, such as injury to thenerve root and dural sac, perineural scar formation, reherniation at thesurgical site and instability due to excess bone removal.

Other attempts have been made for minimally invasive procedures tocorrect symptomatic spinal conditions. One example is chemonucleolysiswhich involved the injection of an enzyme into the disc to partiallydissolve the nucleus to alleviate disc herniation. Unfortunately, theenzyme, chymopapain, has been plagued by concerns about both itseffectiveness and complications such as severe spasms, post-operativepain and sensitivity reactions including anaphylactic shock.

The development of percutaneous spinal procedures has yielded a majorimprovement in reducing recovery time and post-operative pain becausethey require minimal, if any, muscle dissection and they can beperformed under local anesthesia. For example, U.S. Pat. No. 4,545,374to Jacobson discloses a percutaneous lumbar discectomy using a lateralapproach, preferably under fluoroscopic X-ray. This procedure is limitedbecause it does not provide direct visualization of the discectomy site.

Other procedures have been developed which include arthroscopicvisualization of the spine and intervening structure. U.S. Pat. Nos.4,573,448 and 5,395,317 to Kambin disclose percutaneous decompression ofherniated discs with a posterolateral approach. Fragments of theherniated disc are evacuated through a cannula positioning against theannulus. The '317 Kambin patent discloses a biportal procedure whichinvolves percutaneously placing both a working cannula and avisualization cannula for an endoscope. This procedure allowssimultaneous visualization and suction, irrigation and resection in discprocedures.

Unfortunately, disadvantages remain with these procedures andaccompanying tools because they are limited to a specific application orapproach. For example, Jacobson, Kambin, and other references require alateral or a postero-lateral approach for percutaneous discectomy. Theseapproaches seek to avoid damage to soft tissue structures and the needfor bone removal because it was thought to be impractical to cut andremove bone through a channel. However, these approaches do not addressother spinal conditions which may require a mid-line approach, removalof bone, or insertion of implants or other technique.

U.S. Pat. No. 5,439,464 to Shapiro discloses a method and instrumentsfor performing arthroscopic spinal surgeries such as laminectomies andfusions with a mid-line or medial posterior approach using threecannulae. Each of the cannulae requires a separate incision. WhileShapiro discloses an improvement over prior procedures which werelimited to a postero-lateral or lateral approach for disc work,Shapiro's procedure still suffers from many of the disadvantages ofknown prior percutaneous spinal surgery techniques and tools. Onedisadvantage of the Shapiro procedure is its requirement of a fluid workspace. Another significant detriment is that the procedure requiresmultiple portals into the patient.

Fluid is required in these prior procedures to maintain the workingspace for proper function of optics fixed within a prior art cannula andinserted percutaneously. Irrigation, or the introduction of fluid intothe working space, can often be logistically disadvantageous and evendangerous to the patient for several reasons. The introduction of fluidinto the working space makes hemostasis more difficult and may damagesurrounding tissue. Excess fluid may dangerously dilute the sodiumconcentration of the patient's blood supply which can cause seizures orworse. The fluid environment can also make drilling difficult due tocavitation. The requirement for a fluid environment generally increasesexpenses associated with the surgery and adds to the complexity of thesurgery, due in part to the relatively high volume of fluid required.

A need has remained for devices and methods that provide forpercutaneous minimally invasive surgery for all applications andapproaches. A need has also remained for percutaneous methods anddevices which do not require a fluid-filled working space, but that canbe adapted to a fluid environment if necessary.

A significant need is also present in this field for techniques andinstruments that permit surgical procedures in the working space underdirect vision while employing microscopic and endoscopic viewingsystems. Procedures that reduce the number of entries into the patientare also highly desirable. The fields of spinal and neuro surgeryparticularly require devices and techniques that minimize the invasioninto the patient and that are streamlined and concise in theirapplication.

SUMMARY

The present invention is directed to methods and devices for performingsurgery in a patient. In one preferred form, the present inventioncontemplates a cannula that includes a working channel to provide accessto a location in the patient along with the selective employment of anendoscopic viewing system or a microscopic viewing system to view thelocation through the working channel. In another preferred form, thepresent invention contemplates mounting of a clamp assembly on theproximal end of a cannula. The clamp assembly includes a viewing elementmounting portion having a length along which a viewing element can beselectively positioned.

The present invention further contemplates an elongated cannula sizedfor introduction into a patient. The cannula defines a length and aworking channel between a distal working end and an opposite proximalend. A clamp assembly having a viewing element mounting portion can beengaged to the cannula with the viewing element mounting portionextending proximally from the cannula. A viewing element can beselectively engaged at various positions along the length of the viewingelement mounting portion.

In a further form, the present invention contemplates a device forsupporting a viewing element during surgery in a patient. The deviceincludes a cannula having a working channel defined by an inner surfacethat extends between a proximal end and a distal end of the cannula. Aclamp assembly is engageable to the cannula by applying a clamping forceto the inner surface and the outer surface of the cannula. The clampassembly includes a viewing element mounting portion that extendsproximally from the cannula. In one embodiment, the clamp assemblyincludes a foot that extends from the viewing element mounting portion.The foot has a channel positionable over the proximal end of thecannula. A lever arm is pivotably attached to the foot. The lever armincludes a cam member with a cam surface frictionally engageable to theouter surface of the cannula.

In yet another form, a device for performing surgery in a patient isprovided that includes a cannula with a distal working end and aproximal end and a working channel extending therethrough. The cannulahas a length between the proximal end and the distal end such that theproximal end is positioned at the skin level of the patient when saiddistal end is positioned at a desired location in the patient. A clampassembly that supports a viewing element is engageable to the proximalend of the cannula. In a preferred form the viewing element includes anoptics cannula that extends into the working channel.

According to another aspect of the invention, a kit for use inpercutaneous surgery is provided. The kit includes an elongated cannulahaving a working channel extending between a distal working end and anopposite proximal end. The kit further includes a clamp assemblyreinovably engageable to the cannula and a viewing element supportableby the clamp assembly with an optics cannula of the viewing element inthe working channel. The kit also includes a microscope positionableover the proximal end of the cannula.

The present invention also contemplates surgical methods and techniquesemploying the instruments and devices described herein.

These and other aspects, forms, features, objects, and advantages arefurther described in the following description of the illustratedembodiments.

DESCRIPTION OF THE FIGURES

FIG. 1 is a side elevational view of a device according to thisinvention.

FIG. 2 is a top elevational view of a fixture for supporting a viewingdevice within a cannula according to this invention.

FIG. 3 is a side cross-sectional view of the fixture shown in FIG. 2.

FIG. 4 is a side elevational view of a retractor according to oneembodiment of this invention.

FIG. 4A is an end cross-sectional view of the retractor of FIG. 4 takenalong lines A—A.

FIG. 5 is a top elevational view of the retractor shown in FIG. 4.

FIG. 6 is an end elevational view of the retractor shown in FIGS. 4 and5.

FIG. 7 is a side elevational view of a retractor according to anotherembodiment of this invention.

FIG. 7A is an end cross-sectional view of the retractor of FIG. 7 takenalong lines A—A.

FIG. 7B is an end cross-sectional view of the retractor of FIG. 7 takenalong lines B—B.

FIG. 8 is a top elevational view of the retractor shown in FIG. 7.

FIG. 9 is a side elevational view of a dilator according to thisinvention.

FIGS. 10( a)–(i) depicts the steps of a method according to thisinvention.

FIG. 11 is a side cross-sectional view of a device according to oneembodiment of this invention.

FIG. 12 is a side cross-sectional view of an aspiration cap as shown inFIG. 11.

FIG. 13 is a top perspective view of a device according to anotherembodiment of the present invention.

FIG. 14 is a side perspective view of a fixture for supporting a viewingdevice forming part of the device shown in FIG. 13.

FIG. 15 is a side elevational view of the device depicted in FIG. 13with the device shown connected to optical equipment depicted in phantomlines.

FIG. 16 is a side elevational view of a scope body forming part of thefixture depicted in FIGS. 13 and 14.

FIG. 17 is a bottom elevational view of the scope body shown in FIG. 16.

FIG. 18 is a top elevational view of a lever arm forming part of abarrel clamp mechanism used with the fixture depicted in FIG. 14.

FIG. 19 is an end cross-sectional view of the lever arm shown in FIG. 18taken along line 19—19 as viewed in the direction of the arrows.

FIG. 20 is a top elevational view of a barrel cam forming part of abarrel clamp mechanism incorporated into the fixture depicted in FIG.14.

FIG. 21 is a side elevational view of the barrel cam shown in FIG. 20.

FIG. 22 is a bottom assembly view showing the assembly of the lever armof FIGS. 18–19, the barrel cam of FIGS. 20–21 with the scope body shownin FIG. 14.

FIG. 23 is a side elevational view of a scope body as depicted in FIG.14 connected to an aspiration circuit.

FIG. 24 is a cross-sectional view of a human patient at a lumbarvertebral level with a device according to one embodiment of theinvention situated within the patient to define a working channel abovethe laminae of the vertebra.

FIG. 25 is a side elevational view of a tissue retractor incorporatingan optical viewing device.

FIG. 26 is a top elevational view of the tissue retractor incorporatingan optical viewing device as shown in FIG. 25.

FIG. 27 is a side perspective view of a device according to anotherembodiment of the present invention.

FIG. 27 a is a section view along line 27 a—27 a of FIG. 27.

FIG. 28 is a side perspective view of a modular clamp and endoscopeassembly forming part of the device of FIG. 27.

FIG. 29 is a side perspective view of one embodiment of a modular clampfor use with the assembly of FIG. 28.

FIG. 30 is a side perspective view of one embodiment of an endoscope foruse with the assembly of FIG. 29.

FIG. 31 is a side elevational view of a coupling mechanism forming apart of the assembly of FIG. 28.

FIG. 32 is a partially fragmented cross-sectional view of the devicetaken along line 32—32 of FIG. 27.

FIG. 33 is a perspective view of one embodiment of a lever arm formingpart of the barrel clamp mechanism shown in FIG. 32.

FIG. 34 is a perspective view of another embodiment of a lever armforming part of the barrel clamp mechanism of FIG. 32.

FIG. 35 is a partially fragmented cross-sectional view of an alternateembodiment of the device illustrated in FIG. 32.

FIG. 36 is a sectional view of an alternate embodiment cross-section ofa cannula for use with the present invention.

FIG. 37 is a sectional view of another alternate embodimentcross-section of a cannula for use with the present invention.

FIG. 38 is a perspective view of a device according to a furtherembodiment of the present invention.

FIG. 39 is a perspective view of a cannula comprising a portion of thedevice of FIG. 38.

FIG. 40 is a perspective view looking up at a clamp assembly comprisinga portion of the device of FIG. 38 detached from the cannula of FIG. 39.

FIG. 41 is another perspective view looking down at the clamp assemblyrotated about 90 degrees around its central vertical axis from itsposition of FIG. 40.

FIG. 42 is a perspective view looking down at the clamp assembly withthe clamp assembly having generally the same orientation about itscentral vertical axis as in FIG. 40.

FIG. 43 is another perspective view looking down at the clamp assemblyrotated about 180 degrees around its central vertical axis from itsposition of FIG. 40.

FIG. 44 is side elevational view of a lever arm comprising a portion theclamp assembly of FIG. 40.

FIG. 45 is a bottom plan view of the lever arm of FIG. 44.

FIG. 46 is an elevational view of a fastener for securing the lever armof FIG. 44 to the clamp assembly of FIG. 40.

FIG. 47 is an elevational view of a roller pin for moving a viewingelement along a portion of the clamp assembly of FIG. 40.

FIG. 48 is a section view taken through line 48—48 of FIG. 47.

FIG. 49 is a perspective of the device of FIG. 38 according to anotherembodiment of the present invention.

FIG. 50 is a perspective view of a clamp assembly comprising a portionof the device of FIG. 49.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended, such alterations and furthermodifications in the illustrated devices and described methods, and suchfurther applications of the principles of the invention as illustratedtherein being contemplated as would normally occur to one skilled in theart to which the invention relates.

The present invention provides instruments and methods for performingpercutaneous surgery, including spinal applications such as laminotomy,laminectomy, foramenotomy, facetectomy or discectomy, with a singleworking channel endoscope. The present inventors have discovered thatmany percutaneous surgeries may be performed without a fluid workspacethrough the use of optics which move independently of the cannula. Thepresent invention contemplates techniques and instruments that can beimplemented with or without a fluid environment.

This invention also brings the advantages of percutaneous procedures toapplications that previously required open surgery. One advantage isbased upon the further discovery that bone work can be performedpercutaneously through a large working channel. Another advantage isrealized in the use of a single portal within the patient to perform awide range of simultaneous procedures.

According to one embodiment of the present invention, as depicted inFIG. 1, a device 10 is provided for use in percutaneous surgery whichincludes an elongated cannula 20 having a first inner diameter D₁ and anouter diameter D₀ sized for percutaneous introduction into a patient.The cannula 20 also includes a distal working end 21 and an oppositeproximal end 22. The cannula defines a working channel 25 between theends 21, 22 having a second diameter d₂ equal to the first innerdiameter D₁ sized for receiving a tool therethrough. The cannula has alength along its longitudinal axis L that is sized to pass through thepatient from the skin to an operative site or working space. In somecases, the working space may be adjacent a vertebra or disc, or in thespinal canal.

An elongated viewing element 50 is mountable inside cannula 20 adjacentthe working channel 25. The viewing element 50 has a first end 51connectable to a viewing apparatus, such as an eyepiece or camera, andan opposite second end 52 disposed or positionable adjacent the distalworking end 21 of the cannula 20. The particular elongated viewingelement 50 is not critical to the invention. Any suitable viewingelement is contemplated that creates an optical or image transmissionchannel. In one embodiment, the elongated viewing element 50 includes afiber optic scope 54 and a lens 55 at the second end 52. Preferably, thefiber optic scope includes illumination fibers and image transmissionfibers (not shown). Alternatively, the viewing element may be a rigidendoscope or an endoscope having a steerable or bendable tip.

One advantage of this invention is that it provides optics which aremovable relative to the cannula 20. Because the optics are movable, itis not necessary to provide a fluid-maintained work space. The opticscan be removed, cleaned and replaced while the cannula is percutaneouslypositioned within the patient over the working space. Any configurationwhich allows the optics to be movably supported adjacent the workingchannel 25 is contemplated. In one embodiment, shown in FIGS. 1–3, afixture 30 is provided for mounting the elongated viewing element 50 tothe cannula 20. Preferably, the fixture 30 includes a housing 31attachable to the proximal end 22 of the cannula 20. The working channelopening 35 is sized to substantially correspond to the second diameterd₂ of the working channel 25 to receive tools. The fixture 30 includes ahousing 31 which defines a working channel opening 35 arranged tocommunicate with the working channel 25 when the fixture 30 is mountedto the cannula 20. The working channel opening 35 is sized to receivetools therethrough for passage through the working channel 25. In theembodiments shown in FIGS. 1–3, the fixture 30 is configured to mountthe viewing element 50 within the working channel 25.

The housing 31 also defines an optics bore 60 adjacent the workingchannel opening 35. The optics bore 60 has a longitudinal axis l that ispreferably substantially parallel to the axis L of the cannula andworking channel. The optics bore 60 is preferably sized to removablyreceive the elongated viewing element 50 therethrough. The fixture 30preferably supports the viewing element 50 for movement within theoptics bore 60 along the longitudinal axis l of the bore 60 to extend orretract the lens 55 relative to the distal working end 21 of the cannula20. The retractable/extendable feature of the optics of this inventionprovides an advantage over prior endoscopes because it eliminates therequirement for a fluid workspace. While the device 10 and its viewingelement 50 can be easily used in a fluid environment, the fluid is notessential for the system to operate, contrary to prior systems.Furthermore, many of the prior endoscopes were not suited to accesscertain areas because of their large diameters. For example, priorendoscopes could not access the spinal canal. However, with thisinvention, access to the spinal canal is not limited by the diameter ofthe channel or cannula. The cannula 20 can be left behind in the softtissue or supported by the lamina while the second end 52 of theelongated viewing element 50 can be advanced into the spinal canal alongwith any spinal instruments which have been inserted into the workingchannel 25.

Preferably the fixture 30 also supports the viewing element 50 for therotation within the optics bore 60 about the longitudinal axis l of thebore 60. The lens 55 of the viewing element 50 defines an optical axisA₀. As in many endoscopes, the optical axis A₀ can be offset at an anglerelative to the longitudinal axis l of the optics bore 60. This featureallows the optical axis A₀ of the lens to be swept through a conicalfield of the view F for greater visibility of the working space. Thefixture 30 can further be configured so that the viewing element 50 isrotatable relative to the cannula 20. In this embodiment, the housing 31is rotatable relative to the cannula 20 so that the second longitudinalaxis l of the optics bore 60 rotates about the longitudinal axis L ofthe working channel 25. The rotatable features of this invention allowsvisualization of the entire working space. This feature also aids insimplifying the surgical procedure because the optics 50 andaccompanying fittings can be moved out of the way of the surgeon's handsand tools passing through the working channel.

In one embodiment depicted in FIG. 3, the housing 31 defines a receiverbore 40 having an inner diameter d₁ slightly larger than the outerdiameter D₀ of the cannula 20. In this configuration, the proximal end22 of the cannula 20 can be received within the receiver bore 40 so thatthe housing 31 can rotate about the proximal end 22 of the cannula 20.As shown in FIG. 3, the housing 31 also includes an upper bore 41 whichis contiguous with the working channel opening 35 and the receiver bore40. In one embodiment, the optics bore 60 is disposed within the upperbore 41 of the housing 31.

In a preferred embodiment depicted in FIG. 2, the optics bore 60 isdefined by a C-shaped clip 61 disposed within the upper bore 41.Preferably, the C-shaped clip 61 is formed of a resilient material andthe optics bore 60 defined by the clip 61 has an inner diameter D_(i)that is slightly less than the outer diameter of the elongated viewingelement 50. When the viewing element 50 is pushed into the optics bore60 it resiliently deflects the C-shaped clip 61. The resilience of theclip 61 provides a gripping force on the element 50 to hold it in thedesired position, while still allowing the element 50 to berepositioned. Alternatively, the optics bore 60 can have an innerdiameter larger than the outer diameter of the viewing element. In thisinstance, the viewing element 50 can be supported outside the device 20,either manually or by a separate support fixture.

Preferably the device 10 provides engagement means for securely yetrotatably engaging the fixture 30 to the cannula 20. Most preferably,the fixture 30 is configured to engage a standard cannula 20. Engagementmeans can be disposed between the housing 31 and the cannula 20 when thefixture 30 is mounted to the proximal end 22 of the cannula 20 forproviding gripping engagement between the housing 31 and the cannula 20.In one embodiment depicted in FIG. 3 the engagement means includes anumber of grooves 32 within the receiver bore 40 and a resilient sealingmember, such as an O-ring (see FIG. 11) disposed in each groove 32. Thesealing members, or O-rings, disposed between the housing 31 and theouter diameter D₀ of the cannula 20 rotatably secure the fixture 30 tothe cannula 20. The O-rings provide sufficient resistance to movement tohold the fixture 30 in a selected position on the cannula. In anotherembodiment, the housing 31 defines a receiver bore 40 which has an innerdiameter d₁ which is only slightly larger than the outer diameter D₀ ofthe cannula 20 so that the housing 31 can rotate freely about thecannula 20.

The working channel 25 and the working channel opening 35 are both sizedto receive a tool or instrument therethrough. Preferably, the workingchannel opening 35 of the housing 31 has a diameter Dw which issubstantially equal to the inner diameter d₂ of the working channel 25so that the effective diameter of the working channel is not reduced bythe fixture 30. This configuration provides a maximum amount of spacefor the insertion of tools into the working channel 25. The presentinvention is advantageous because standard micro-surgical spinal toolscan be inserted into the working channel and manipulated to perform asurgical procedure. The present invention is particularly advantageousbecause the working channel 25 will simultaneously accept a plurality ofmovable instruments. No other known prior art device has a workingchannel that accepts more than one movable instrument at a time througha single port. Therefore, according to this invention, an entirepercutaneous surgical procedure can be performed through the workingchannel 25 of the device 10 under direct visualization using the viewingelement 50 disposed within the optics bore 60.

In accordance with the present embodiment, the components of the device10 are cylindrical in configuration. In other words, the cannula 20,working channel 25 and fixture 30 have corresponding cylindricalconfigurations which yield the various diameters D_(i), D_(o), D_(w) andd₂. In accordance with other embodiments contemplated as part of theinvention, these diameters may be non-circular inner and outerdimensions, such as oval or square shaped. For example, a cannula 20modified to a square cross-section, such as illustrated in FIG. 37,would still provide a large working channel, such as working channel 25.In another embodiment, the cross-section is oval, such as thatillustrated in FIG. 36.

Likewise, a corresponding fixture 30 have a square cross-section wouldalso provide a large working channel opening D_(w). In the case of thenon-circular configurations, the fixture 30 in accordance with thepresent embodiment would be unable to rotate around the circumference ofthe cannula 20, as permitted by the circular configurations. On theother hand, even the non-circular configurations will permit axialmovement of the optical viewing element and rotation of the viewingelement about its own axis, as set forth more fully herein.

In accordance with a further variation of the present invention, thecannula 20 can be replaced by a similar device that is capable ofmaintaining a large working channel 25. For example, the cannula 20 canbe replaced by an expanding cannula or dilator apparatus. In onespecific embodiment, the apparatus can be a spiral wound tube that isunwound or expanded to provide the working channel dimension.Alternatively, multiple tissue dilators, such as speculae, can beexpanded to create a working space. In these configurations, the fixture30 may still be used to support the optical viewing element 50 once theexpandable dilator or tissue retractor reaches its full working channeldimension.

Although standard micro-surgical instruments may be used with thepresent invention, this invention also contemplates certain novel toolswhich capitalize on and enhance the advantages of this invention.

According to one preferred embodiment of the invention, a tissueretractor 70 is provided as depicted in FIGS. 4–6. The retractor 70 isremovably and rotatably insertable through the working channel 25 andthe working channel opening 35 of the device 10. The tissue retractor 70includes a working tip 75 configured to atraumatically displace tissueas the retractor 70 is manipulated through the tissue and a body 76having a proximal first end 77 and a distal second end 78. The secondend 78 can be integral with the working tip 75 which preferably has ablunt curved end 82. In addition, the working tip 75 is also preferablybent or curved away from the body 76, as shown in FIG. 4. The body 76 issized to be rotatably received within the cannula 20 and has a length Bfrom the first end 77 to the second end 78 sufficient so that the firstend 77 and the working tip 75 can both extend outside the cannula 20when the body 76 is within the cannula 20.

This invention contemplates any suitable retractor for use through theworking channel 25. However, retractors such as the retractor 70depicted in FIGS. 4–6 are preferred in which the body 76 includes acurved plate 84 that is configured to conform to the inner cylindricalsurface 26 of the cannula without substantially blocking the workingchannel 25. The curved plate 84 has a convex surface 80 and an oppositeconcave surface 81. In one embodiment, the curved plate 84 includes afirst plate portion 85 defining a first convex surface 80 and anopposite first concave surface 81. A second plate portion 86 is integralwith the first plate portion 85 and is disposed between the first plateportion 85 and the working tip 75. The second plate portion 86 defines asecond convex surface (not shown) and an opposite second concave surface81′. Both the first plate portion 85 and the second plate portion 86include opposite edges 90 extending substantially parallel to the lengthB of the body 76.

Preferably, the curved plate 84 subtends an arc A₁ between the oppositeedges 90 of at least 200 degrees, and most preferably 270 degrees. In aspecific embodiment, the second plate portion 86 and specifically thesecond concave surface 81′ subtends an angle that decreases along thelength of the retractor. Thus, in one embodiment, the second concavesurface 81′ subtends an angle of about 200 degrees adjacent the firstplate portion 85, decreasing to an angle of less than about 10 degreesat end 78.

An alternate embodiment of a tissue retractor according to thisinvention is depicted in FIGS. 7–8. This retractor 100 has a body 106which includes a first plate portion 115 defining a first convex surface110 and an opposite first concave surface 111 and includes firstopposite edges 120 extending substantially parallel to the length B ofthe body 106. The first plate portion 115 subtends a first arc A₂between the first opposite edges 120. The retractor body 106 alsoincludes a second plate portion 116 which is integral with the firstplate portion 115 and is disposed between the first plate portion 115and a working tip 105. The second plate portion 116 defines a secondconvex surface 110′ and an opposite second concave surface 111′ andincludes second opposite edges 120′ extending substantially parallel tothe length B. The second plate portion 116 subtends a second arc A₃between the second opposite edges 120′ that is different from the firstarc A₂ in this embodiment. Preferably, the first arc A₂ subtends anangle of less than 180 degrees and the second arc A₃ subtends an angleof more than 180 degrees. Most preferably, the first arc A₂ subtends anangle of about 90 degrees and the second arc A₃ subtends an angle ofabout 270 degrees.

The retractors of this invention may be provided with means for engagingthe retractors 70, 100 within the working channel 25 of the cannula 20.For example, the convex surfaces 80, 110 can be configured to have adiameter that is greater than the diameter D₁ of the inner cylindricalsurface 26 of the cannula 20. In that case, the body 76, 106 may beformed of a resilient material that is deformable to be insertable intothe cannula 20 so that the convex surface 80, 110 is in contact with theinner cylindrical surface 26 of the cannula 20. When the body 76, 106 isdeformed, it exerts an outward force against the surface 26 tofrictionally hold the retractor in its selected position.

The preferred components provided by this invention are configured sothat multiple tools and instruments can be accepted and manipulatedwithin the working channel 25 of the cannula 20. The components are alsoconfigured so that more than one surgeon may manipulate instrumentsthrough the working channel 25 of the cannula 20 at one time. Forexample, one surgeon may be manipulating the retractor while anothersurgeon is drilling into a bone. The curvature of the body 76, 106 ofthe retractors 70, 100 provides more working space and increasesvisibility. Another feature is that the long axis of the component canbe placed in the working channel 25 while a bend in the handle portionkeeps hands away from the channel 25 so that more than one surgeon canwork in the channel 25 and more tools can be placed in the channel 25.The retractors shown in FIGS. 4–8 each comprise an arm 71, 101 attachedto the proximal first end 77, 107 of the body 76, 106. Preferably, asshown in FIGS. 4–8, the arm 71, 101 is at an angle α which is less than180 degrees from the longitudinal axis of the length L of the body 76.Most preferably, the angle α is about 90 degrees so that the arm 71, 101is substantially perpendicular to the length L of the body 76, 106.Preferably, the arm 71, 101 has a gripping surface 72, 102 to facilitatemanipulation of the retractor 70, 100.

The present invention also provides tissue dilators usable with thedevice 10. Any dilator which is insertable into the working channel 25of the cannula 20 is contemplated; however, a preferred dilator providedby this invention is depicted in FIG. 9. A dilator 130 preferablyincludes a hollow sleeve 135 defining a channel 131. The channel 131allows the dilator 130 to be placed over a guidewire (not shown) orother dilators. The hollow sleeve 135 has a working end 136 defining afirst opening 132 in communication with the channel 131 and an oppositeend 137 defining a second opening 133. The working end 136 is tapered toa tapered tip 138 to atraumatically displace tissue. Preferably, agripping portion 140 is provided on the outer surface 141 of the sleeve135 adjacent the opposite end 137. In one embodiment, the grippingportion 140 is defined by a plurality of circumferential grooves 142defined in the outer surface 141. The grooves 142 are configured formanual gripping of the dilator 130 to manipulate the dilator 130 throughtissue. Preferably, the grooves 142 are partially cylindrical. In theembodiment shown in FIG. 9, the gripping portion 140 includes a numberof circumferential flats 143 adjacent each of the circumferentialgrooves 142. The grooves 142 have a first width W₁ along the length ofthe sleeve 135 and the flats 143 have a second width W₂ along thelength. Preferably, the first and second width W₁ and W₂ aresubstantially equal.

The present invention has application to a wide range of surgicalprocedures, and particularly spinal procedures such as laminotomy,laminectomy, foramenotomy, facetectomy and discectomy. Prior surgicaltechniques for each of these procedures has evolved from a grosslyinvasive open surgeries to the minimally invasive techniques representedby the patents of Kambin and Shapiro. However, in each of theseminimally invasive techniques, multiple entries into the patent isrequired. Moreover, most of the prior minimally invasive techniques arereadily adapted only for a posterolateral approach to the spine. Thedevices and instruments of present invention have application in aninventive surgical technique that permits each of these several types ofsurgical procedures to be performed via a single working channel. Thisinvention can also be used from any approach and in other regionsbesides the spine. For instance, the invention contemplates apparatusappropriately sized for use in transnasal, transphenoidal and pituitarysurgeries.

The steps of the spinal surgical procedure in accordance with one aspectof the present invention are depicted in FIG. 10. As can be readily seenfrom each of the depicted steps (a)–(i), the present embodiment of theinvention permits a substantially mid-line or medial posterior approachto the spine. Of course, it is understood that many of the followingsurgical steps can be performed from other approaches to the spine, suchas posterolateral and anterior. In a first step of the technique, aguidewire 150 can be advanced through the skin and tissue into thelaminae M of a vertebral body V. Preferably, a small incision is made inthe skin to facilitate penetration of the guidewire through the skin. Inaddition, most preferably the guidewire, which may be a K-wire, isinserted under radiographic or image guided control to verify its properpositioning within the laminae M of the vertebra V. It is, of course,understood that the guidewire 150 can be positioned at virtually anylocation in the spine and in any portion of a vertebra V. Thepositioning of the guidewire is dependent upon the surgical procedure tobe conducted through the working channel cannula of the presentinvention. Preferably, the guidewire 150 is solidly anchored into thevertebral bone, being tapped by a mallet if necessary.

In subsequent steps of the preferred method, a series of tissue dilatorsare advanced over the guidewire 150, as depicted in steps (b)–(d) inFIG. 10. Alternatively, the dilators can be advanced through theincision without the aid of a guidewire, followed by blunt dissection ofthe underlying tissues. In the specific illustrated embodiment, a seriesof successively larger dilators 151, 152 and 153 are concentricallydisposed over each other and over the guidewire 150 and advanced intothe body to sequentially dilate the perispinous soft tissues. Mostpreferably, the tissue dilators are of the type shown in FIG. 9 of thepresent application. In a specific embodiment, the dilators havesuccessively larger diameters, ranging from 5 mm, to 9 mm to 12.5 mm forthe largest dilator. Other dilator sizes are contemplated depending uponthe anatomical approach and upon the desired size of the workingchannel.

In the next step of the illustrated technique, the working channelcannula 20 is advanced over the largest dilator 153, as shown in step(e), and the dilators and guidewire 150 are removed, as shown in step(f). Preferably, the working channel cannula 20 has an inner diameter D₁of 12.7 mm so that it can be easily advanced over the 12.5 mm outerdiameter of the large dilator 153. Larger working channel cannulas arecontemplated depending upon the anatomical region and surgicalprocedure.

With the cannula 20 in position, a working channel is formed between theskin of the patient to a working space adjacent the spine. It isunderstood that the length of the cannula 20 is determined by theparticular surgical operation being performed and the anatomysurrounding the working space. For instance, in the lumbar spine thedistance between the laminae M of a vertebra V to the skin of thepatient requires a longer cannula 20 than a similar procedure performedin the cervical spine where the vertebral body is closer to the skin. Inone specific embodiment in which the cannula 20 is used in a lumbardiscectomy procedure, the cannula has a length of 87 mm, althoughgenerally only about half of the length of the cannula will be situatedwithin the patient during the procedure.

In accordance with the present surgical technique, the working channelcannula 20 is at least initially only supported by the soft tissue andskin of the patient. Thus, in one aspect of the preferred embodiment,the cannula 20 can include a mounting bracket 27 affixed to the outersurface of the cannula (FIG. 10( f), FIG. 11). This mounting bracket 27can be fastened to a flexible support arm 160, which can be of knowndesign. Preferably, the flexible support arm 160 is engaged to thebracket 27 by way of a bolt and wing nut 161, as shown in FIG. 10( i)and in more detail in FIG. 11, although other fasteners are alsocontemplated. This flexible arm 160 can be mounted to the surgical tableand can be readily adjusted into a fixed position to provide firmsupport for the cannula 20. The flexible arm 160 is preferred so that itcan be contoured as required to stay clear of the surgical site and toallow the surgeons adequate room to manipulate the variety of tools thatwould be used throughout the procedure.

Returning to FIG. 10, once the cannula 20 is seated within the patient,the fixture 30 can be engaged over the proximal end of the cannula 20.The fixture 30, as shown in FIGS. 2 and 3 and as described above,provides an optics bore 60 for supporting an elongated viewing element,such as element 50 shown in step h. In accordance with the invention,the viewing element 50 is advanced into the fixture 30 and supported bythe optics bore 60 (FIG. 2). In one specific embodiment, the element 50is most preferably a fiber optic scope, although a rod lens scope, “chipon a stick” or other viewing scopes may be utilized. In the final step(i) of the procedure shown in FIG. 10, the flexible arm 160 is mountedto the bracket 27 to support the cannula 20 which in turn supports theoptical viewing element 50. This final position of step (i) in FIG. 10is shown in more detail in FIG. 11. The viewing element 50 can be avariety of types, including a rigid endoscope or a flexible andsteerable scope.

With the viewing element or scope 50 supported by the fixture 30 thesurgeon can directly visualize the area beneath the working channel 25of the cannula 20. The surgeon can freely manipulate the viewing element50 within the working channel 25 or beyond the distal end of the cannulainto the working space. In the case of a steerable tip scope, the secondend 52 of the viewing element 50, which carries the lens 55, can bemanipulated to different positions, such as shown in FIG. 11. Withvirtually any type of viewing element, the manipulation and positioningof the scope is not limited by the working channel 25, in contrast toprior systems.

Preferably, the positioning capability provided by the fixture 30 isutilized to allow extension of the lens 55 into the working space orretraction back within the cannula 20, as depicted by arrows T inFIG. 1. Also the fixture preferably accommodates rotation of theelements 50 about its own axis (arrows R in FIG. 1) to vary the viewingangle provided by the angled lens 55, or rotation of the entire viewingelement 50 about the cannula 20 and around the circumference of theworking channel 25, as shown by the arrows N in FIG. 1. In this manner,the surgeon is provided with a complete unrestricted view of the entireworking space beneath the working channel 25. In instances when thefixture 30 is rotated about the cannula 20, the viewing orientation ofthe optics (i.e. left-right and up-down) is not altered so the surgeon'sview of the procedure and surrounding anatomy is not disturbed.

Another advantage provided by the single working channel cannula 20 ofthe present invention, is that the cannula can be readily positionedover an appropriate target tissue or bone, to thereby move the workingspace as necessary for the surgical procedure. In other words, since theworking channel cannula 20 is freely situated within the patient's skinand tissue, it can be manipulated so that the working space beneath thecannula 20 is more appropriately centered over the target region of thespine. Repositioning of the cannula 20 can be performed underfluoroscopic guidance. Alternatively, the cannula may be fitted withposition sensing devices, such as LEDs, to be guided stereotactically.As the cannula is being repositioned, the surgeon can also directlyvisualize the spine through the viewing element 50.

Once the position of the cannula 20 is established and a working spaceis oriented over the proper target tissue, a variety of tools andinstruments can be extended through the working channel 25 to accomplishthe procedure to be performed. For instance, in the case of alaminotomy, laminectomy, foramenotomy or facetectomy, a variety ofrongeurs, curettes, and trephines can be extended through the workingchannel opening 35 (see FIG. 2) and through the working channel 25 ofthe cannula 20 (see FIG. 11) into the working space. It is understoodthat these various tools and instruments are designed to fit through theworking channel. For instance, in one specific embodiment, the workingchannel 25 through the cannula 20 can have a maximum diameter d₂ of 12.7mm. However, with the viewing element 50 extending into the workingchannel 25, the effective diameter is about 8 mm in the specificillustrated embodiment, although adequate space is provided within theworking channel 25 around the viewing element 50 to allow a wide rangeof movement of the tool or instrument within the working channel. Thepresent invention is not limited to particular sizes for the workingchannel and effective diameter, since the dimensions of the componentswill depend upon the anatomy of the surgical site and the type ofprocedure being performed.

Preferably, each of the tools and instruments used with the workingchannel cannula 20 are designed to minimize obstruction of the surgeon'svisualization of and access to the working space at the distal end ofthe working channel cannula. Likewise, the instruments and tools aredesigned so that their actuating ends which are manipulated by thesurgeon are displaced from the working channel cannula 20. One suchexample is the tissue retractor shown in FIGS. 4–8. With theseretractors, the handles that are manually gripped by the surgeon areoffset at about a 90 degree angle relative to the longitudinal axis ofthe tool itself.

In accordance with once aspect of the present invention, the surgicalprocedures conducted through the working channel cannula 20 and withinthe working space at the distal end of the cannula are performed“dry”—that is, without the use of irrigation fluid. In prior surgicaltechniques, the working space at the surgical site is fluid filled tomaintain the working space and to assist in the use of the visualizationoptics. However, in these prior systems the visualization optics werefixed within the endoscope. In contrast, the device 10 of the presentinvention allows a wide range of movement for the viewing element 50 sothat the lens 55 can be retracted completely within the working channel25 of the cannula 20 to protect it from contact with the perispinoustissue or blood that may be generated at the surgical site.

Moreover, since the viewing element 50 is removable and replaceable, theelement 50 can be completely removed from the fixture 30 so that thelens 55 can be cleaned, after which the viewing element 50 can bereinserted into the fixture and advanced back to the working space.Under these circumstances, then the need for irrigation is lesscritical. This feature can be of particular value when cuttingoperations are being performed by a power drill. It has been found inprior surgical procedures that the use of a power drill in a fluidenvironment can cause turbulence or cavitation of the fluid. Thisturbulence can completely shroud the surgeon's view of the surgical siteat least while the drill is being operated. With the present invention,the dry environment allows continuous viewing of the operation of thepower drill so that the surgeon can quickly and efficiently perform thenecessary cutting procedures.

While the present invention permits the surgeon to conduct surgicalprocedures in the working space under a dry environment, irrigation maybe provided separately through the working channel 25. Alternatively,the viewing device 50 itself may include a tube 54 supported by thefitting 53 through which modest amount of fluid can be provided to keepthe visualization space clear. In addition, during a discectomy,aspiration of the excised tissue is preferred, and irrigation willfrequently assist in rapid removal of this tissue. Thus, separateirrigation and aspiration elements can also be inserted through theworking channel 25 as required by the procedure.

As necessary, aspiration can be conducted directly through the workingchannel 25 of the cannula 20. In one specific embodiment, an aspirationcap 165 is provided as shown in FIGS. 11 and 12. The cap 165 includes abody 166 which defines a mating bore 167 having an inner diameter d_(b)larger than the outer diameter D_(h) of the housing 31 of fitting 30. Atool opening 168 is provided in communication with the mating bore 167.When the aspiration cap 165 is mounted over the housing 31, as shown inFIG. 11, the tool opening 168 communicates directly with the upper bore41 and provides the same entry capabilities as the working channelopening 35 of the housing 31. The aspiration cap 165 is also providedwith a tube receiver bore 169 which intersects the mating bore 167. Thereceiver bore 169 is configured to receive an aspiration tube throughwhich a vacuum or suction is applied. In certain instances, the toolopening 168 may be covered while suction is applied through the toolreceiver bore 169 and mating bore 167, and ultimately, through theworking channel 25. Covering the opening 168 can optimize the aspirationeffect through the working channel.

Returning again to the surgical technique of one embodiment of thepresent invention, once the working channel cannula 20 and the optics 50are in position, as depicted in FIG. 10 step (i) and FIG. 11, theparaspinous tissue can be retracted using instruments as describedabove, and a laminectomy performed using various rongeurs, curettes anddrills. As necessary, the cannula 20 can be angled to allow a greaterregion of bone removal, which may be necessary for access to otherportions of the spinal anatomy. In some instances, access to the spinalcanal and the posterior medial aspects of the disc annulus may requirecutting a portion of the vertebral bone that is greater than the innerdiameter of the working channel 25. Thus, some manipulation of thecannula 20 may be necessary to permit removal of a greater portion ofbone. In other operations, multi-level laminectomies or foramenotomiesmay be necessary. In this instance, these multi-level procedures can beconducted by sequentially inserting the working channel cannula 20through several small cutaneous incisions along the spinal mid-line.Alternatively, several working channel cannulas 20 can be placed at eachof the small cutaneous incisions to perform the multi-level bone removalprocedures.

Again, in accordance with the preferred illustrated surgical technique,an opening is cut into the laminae M of the vertebra V providing directvisual access to the spinal canal itself. As necessary, tissuesurrounding the spinal nerve root can be removed utilizingmicro-surgical knives and curettes. Once the spinal nerve root isexposed, a retractor, such as the retractors shown in FIGS. 4–8, can beused to gently move and hold the nerve root outside the working space.In one importance aspect of the two retractors 70, 100, the portion ofthe retractor passing through the working channel 25 generally conformsto the inner surface of the cannula 20 so that the working channel 25 isnot disrupted by the retractor tool. Specifically, the effectivediameter within the working channel 25 is reduced only by the thicknessof the curved plates 84, 114 of the retractors 70, 100. In one specificembodiment, this thickness is about 0.3 mm, so it can be seen that thetissue retractors do not significantly reduce the space available in theworking channel 25 for insertion of other tools and instruments.

With the tissue retractor in place within the working channel 25, bonewithin the spinal canal, such as may occur in a burst fracture, can beremoved with a curette or a high speed drill. Alternatively, thefractured bone may be impacted back into the vertebral body with a boneimpactor. At this point, if the spinal procedure to be performed is theremoval of epidural spinal tumors, the tumors can be resected utilizingvarious micro-surgical instruments. In other procedures, the dura may beopened and the intradural pathology may be approached withmicro-surgical instruments passing through the working channel cannula20. In accordance with the specific illustrated technique, the nerveroot retracted posterior medial disc herniations can be readily exciseddirectly at the site of the herniation.

In another embodiment of the invention, a working channel cannula, suchas cannula 20, is provided with a fixture 170 for supporting optics andirrigation/aspiration components. In accordance with this embodiment,the fixture 170 includes a scope body 171 which is shown most clearly inFIGS. 13, 14, 16, and 17. The scope body 171 includes a clamping ring172 configured to encircle the outer surfaces 23 of the cannula 20. Inparticular, the clamping ring 172 includes an inner clamping surface 175(see FIG. 14). The clamping surface 175 has substantially the sameconfiguration and dimension as the outer surface 23 of the cannula 20.The clamping ring 172 includes clamp arms 173 a, b at the free ends ofthe ring. The clamp arms 173 a, b define a slot 174 (see FIG. 17)therebetween.

The clamping ring 172 is integral with a support column 176 forming partof the scope body 171. A column slot 177 is formed in the support column176, with the column slot 177 being contiguous with the slot 174 betweenthe clamp arms 173 a, b. As described in more detail herein, the slots174 and 177 permit the clamp arms 173 a, b to be compressed toward eachother to thereby compress the clamping surface 175 of the ring 172 aboutthe outer surface 23 of the cannula 20. In this manner, the fixture 170can be affixed at a specific position on the cannula 20. It isunderstood that when the clamping ring 172 is loosened, the fixture 170is free to rotate about the circumference of the cannula 20 in thedirection of the arrow N. In addition, the fixture 170 can translatealong the longitudinal length of the cannula 20 in the direction of thearrow T. Of course, the direction of the travel distance of the fixture170 along the length of the cannula 20 is limited by the proximal end 22and the bracket 27 used to engage a supporting flexible arm 160 asdescribed above.

Returning to FIGS. 13–17, additional details of the fixture 170 can bediscerned. In particular, the fixture 170 includes an optics mountingbody 178 that is supported by and preferably integral with the supportcolumn 176. The optics mounting body 178 defines a stop edge 179 at theinterface between the support column 176 and the mounting body 178. Thisstop edge defines the height of the support column from the clampingring 172 to the stop edge 179. The stop edge 179 of the optics mountingbody 178 can be used to limit the downward travel of the fixture 171 inthe direction of the arrow T, which can be particularly important inembodiments of the cannula 20 that do not include the bracket 27.

In accordance with the present embodiment, the optics mounting body 178defines an optics bore 180 which is configured to receive and support anoptics cannula 190. The optics bore 180 can communicate with anillumination port 181 which can receive an illumination source, such asa fiber optic light cable. The optics bore 180 also communicates with anoptics coupling bore 182 projecting from a front face of the fixture170. In accordance with one specific embodiment, the fixture 170 alsoincludes a coupling body 183 that is preferably press-fit within theoptics coupling bore 182. As shown in FIG. 15, the coupling body 183 canbe engaged by a coupler 184 to support a camera 185 thereon.

In a further aspect of the optics mounting body 178, an aspiration port186 and an irrigation port 187 can be provided that communicates withthe optics bore 180. Preferably, the optics cannula 190 includeschannels along its length to correspond to the various ports in theoptics mounting body 178. In one specific embodiment, the port 181 isnot used, with the port 186 being used to receive an illuminationelement. As shown more particularly in FIG. 23, the port 187 can beconnected to an aspiration circuit. In particular, the port 187 can beengaged to an aspiration tube 225 which carries a flow control valve 226and Luer® fitting 227 at its free end. The Luer® fitting 227 can engagea source of irrigation fluid or aspiration vacuum pressure dependingupon the particular use envisioned for the port 187 and a correspondingchannel within the optics cannula 190.

In accordance with a method of the present invention, the port 187 isused as an aspiration port with the Luer® fitting 227 connected to avacuum source. It is understood that the port 187 is in fluidcommunication with a corresponding channel in the optics cannula 190 sothat suction applied through the tube 225 and port 187 is drawn throughthe distal or working end 192 of the optics cannula 190. The working end192 is at the surgical site so that the suction draws air through theworking channel 25 of the cannula 20, to the surgical site and throughthe aspiration/irrigation channel in the optics cannula 190. It has beenfound that providing aspiration suction in this manner eliminates smokethat may be developed during operation of certain instruments, such as aBovie. Moreover, the suction applied through the port 187 can draw airacross the lens 191 (see FIG. 14, 15) of the optics cannula 190, toprevent fogging of the lens. If a separate aspiration tube is extendedthrough the working channel, defogging of the lens 191 is best achievedwith the opening of the aspiration tube adjacent the lens. In thismanner, the provision of aspiration vacuum through the working channeland working space virtually eliminates the need to retract the opticscannula 190 to clean the lens 191. This is in contrast to prior devicesin which either the lens had to be removed from the surgical site forcleaning or devices in which substantial flow of fluid is required tokeep the lens clean and clear.

Looking now to FIGS. 18–22, details of a barrel clamp mechanism 195 areshown. The barrel clam mechanism 195 compresses the arms 173 a, b of theclamping ring 172 together to clamp the fixture 170 to the cannula 20.The barrel clamp mechanism 195 includes a barrel cam 196 disposedimmediately adjacent one of the clamp arms 173 b, and a lever arm 197that operates to compress the barrel cam 196 against the clamp arm 173.A shoulder screw 198 fixes each of these components together.Specifically, the shoulder screw 198 includes a threaded shank 199 thatis configured to engage a mating threaded bore 202 in one of the clamparms 173 a. The shoulder screw 198 includes a bearing shank 200 that issmooth or non-threaded. The bearing shank 200 is received within abearing bore 203 in the clamp arm 173 b, a colinear bearing bore 204 inthe barrel cam 196, and a bearing bore 205 in the lever arm 197. Theshoulder screw 198 further includes an enlarged head 201 which ispreferably received within a head recess 206 in the lever arm 197 (seeFIG. 19). Preferably, the enlarged head 201 of the shoulder screwincludes a driving tool recess to mate with a driving tool to thread thethreaded shank 199 of the screw into the mating threaded bore 202 of theclamp arm 173 a. It is understood that the barrel cam 196 and lever arm197 are free to rotate about the bearing shank 200 of the shoulder screw198.

Referring specifically to FIGS. 18–19, the lever arm 197 includes an arm210 that is integral with a body 211. The bearing bore 205 and headrecess 206 are defined in the body 211. The body 211 defines a pair ofprojections 212 on opposite sides of the bearing bore 205. As depictedin FIG. 19, each of the projections 212 includes a rounded tip 213 toprovide a smooth sliding surface.

Referring specifically to FIGS. 20–21, the barrel cam 196 includes aflat face 215 that faces the clamp arm 173 b. Preferably, the flat faceprovides for smooth rotation of the barrel cam 196 relative to thestationary arm 173 b. The opposite face of the barrel cam 196 is a camface 216 that includes a pair of diametrically opposite cam portions217. In accordance with the preferred embodiment, the cam portions 217define a ramp 218 that is inclined upward to a detent recess 219. Eachdetent recess 219 terminates in a stop 220 that is higher relative tothe base detent recess 219 than the ramp 218.

In the assembled configuration, the barrel clamp mechanism 195 operatesto compress the arms 173 a, b of the clamping ring 172 together when thelever arm 197 is rotated about the shoulder screw 198. Specifically, asthe lever arm 197 is rotated, the projections 212 slide on their roundedtip 213 along the ramps 218 until the rounded tips 213 fall within theopposite detents 219. As the projections 212 move up the ramps 218, theprojections 212 push the barrel cam 196 toward the clamp arms 173 a, b.More specifically, since the opposite clamp arm 173 a is held relativelyfixed by the threaded shank 199 of the shoulder screw 198, the movementof the barrel cam 196 presses the clamp arm 173 b against the relativelystationary clamp arm 173 a. As this occurs, the clamping ring 172 istightened around the outer surface 23 of the cannula 20. When theprojections 212 are seated within the recesses 219 of the barrel cam196, the fixture is locked onto the cannula 20. It is understood thatthe recesses 219 are shallow enough to permit ready manual disengagementof the projections 212 from the recesses 219 as the lever arm 197 isrotated in the opposite direction.

In one specific embodiment, the detent recesses 219 are 180° oppositeeach other. The ramps 218 are curved and subtend an angle of about 90°.Thus, the lever arm 197 rotates through 90° to move the projections 212from one end of the cam ramps 218 to the recesses 219. In the preferredembodiment, the lever arm ninety degree movement (arrow J in FIG. 15)moves the arm from a first position in which the arm 197 issubstantially parallel to the cannula, to a second position in which thearm is substantially perpendicular to the cannula. Most preferably, inthe second position the arm is oriented immediately adjacent thecannula, rather than projecting away. In the first and second positions,the lever arm 197 maintains a low profile so as not to interfere withthe surgeon's manipulation of tools and instruments through the workingchannel. In a specific embodiment, the first position of the lever armcorresponds to the loose or unlocked position of the barrel clampmechanism 195, while the second position corresponds to the lockedconfiguration.

In order for the barrel clamp mechanism 195 to function properly, it ispreferred that the barrel cam 196 remain stationary relative to themoveable lever arm 197, with the exception that the barrel cam 196 isfree to translate along the length of the shoulder screw 198.Consequently, the clamp arm 173 b includes a recess 222 that has aconfiguration substantially similar to the outer periphery of the barrelcam 196. In this manner, the barrel cam can be slightly indented withinthe clamp arm 173 b so that the cam is unable to rotate about theshoulder screw 198 as the lever arm 197 is pivoted.

In accordance with one specific embodiment of the invention, thecomponents of the fixture 170 are formed of a flexible and resilientmaterial. For example, the scope body 171 can be formed of a plastic,such as polycarbonate. The scope body 171 lends itself particularly wellto typical plastic molding techniques. Likewise, the barrel cam 196 andlever arm 197 can be molded from a plastic material. In one specificembodiment, these components are formed of Delrin®, since Delrin®provides a smooth surface for the relative movement between theprojection 212 on the lever arm 197 and the cam face 216 of the barrelcam 196.

It is understood that the travel of the barrel clamp mechanism 195 canbe calibrated sufficient to tightly compress the clamping rings 172about the cannula 20. It is also understood that this compression mustnot be so great as to compromise the integrity or strength of thecannula 20. In one specific embodiment, the slot 174 is larger than themaximum travel of the barrel clamp mechanism 195 so that the projections212 of the lever arm 197 can rest solidly within the detent recesses 219of the barrel cam 196. In accordance with one specific embodiment, theslot 174 has a dimension of 2.0 mm while the throw of the barrel clampmechanism 195 achieved by the barrel cam 196 is 1.0 mm.

In accordance with the present embodiment of the invention, the fixture170 supports an optics cannula 190 in a fixed orientation relative tothe scope body 171. In other words, in this specific embodiment, theoptics cannula 190 is not permitted to rotate about its axis as couldthe scope 50 of the embodiment shown in FIG. 1. The lens 191 istherefore mounted at an angle B relative to the distal end of the opticscannula 190. In one specific embodiment, the lens 191 is situated at anangle B of 30°. In addition, in the specific embodiment, the lens has anoptical axis that is angled toward the center of the working space 25 orthe cannula 20. While the lens 191 has a fixed orientation relative tothe scope body 171, the lens can still be rotated around the workingspace by rotation of the fixture 170 about the outer surface 23 of thecannula 20. In addition, the lens 191 and the optical system provide adepth of field of view that allows the surgeon to view anatomy outsidethe working channel 25.

Even in the present specific embodiments, the fixture 170 allowsrotation of the optics cannula 190 around the working space andtranslation of the optics cannula 190 and 191 along the longitudinalaxis of the working channel 25. Of course, it is understood that thesurgeon can achieve these motions by releasing the barrel clampmechanism 195 and then re-engaging the clamp by rotating the lever arm197 to its locked position. Preferably, the optics cannula 19 is sizedso that the lens 191 can project beyond the distal end 21 of the cannula20. Similarly, in the preferred embodiment, the fixture 170 allows theretraction of the lens 191 and optics cannula 190 within the workingchannel 25 and cannula 20.

In one specific embodiment, the fixture 170 permits up to 15 mm travelalong the direction of the arrow T with 7.5 mm of the travel beingwithin the working space 25 and 7.5 mm of the travel being beyond thedistal end 21 of the cannula 20. In accordance with the specificembodiment, this 15 mm travel distance is related to the height of thesupport column 176 from the top of the clamping ring 172 to the stopedge 179 of the optics mounting body 178. The amount of extension of thelens 191 of the optics cannula 190 beyond the distal end 21 of thecannula 20 is also based upon the overall length of the optics cannula190 relative to the overall length of the working channel cannula 20. Inone specific embodiment, the optics cannula 190 has a length of 100 mmmeasured from the lens 191 to the stop edge 179 of the optics mountingbore 178. Of course, it is understood that the optics cannula is longerthan this 100 mm distance because a portion of the cannula is supportedwithin the optics bore 180 of the optics mounting body 178. Again in thespecific embodiment, the cannula 20 has an overall length of 92 mm fromits distal end 21 to its proximal end 22 (see FIG. 15).

In a further aspect of the invention, the overall length of the cannula,and consequently the optics cannula 190, is determined, in part, by thespinal anatomy. In particular, for applications of the present inventionin the field of spinal surgery, it has been found that placement of theproximal end 22 of the working channel 25 too distant from the surgicalsite at the distal end 21 causes the surgeon to lose tactile feel whilemanipulating certain instruments. In other words, when the surgeonpasses instruments through the working channel and manipulates them atthe surgical site, a certain amount of “feel” is required so that thesurgeon can accurately perform the respective operations with theinstrument. If the distance between the surgical site and manual end ofthe instrument is too great, the surgeon will not be able to stably andcomfortably operate the instrument.

In accordance one beneficial aspect of the present invention, it hasbeen found that the working channel cannula 20 must have a length thatis limited relative to the distance L (FIG. 24) between the vertebrallaminae and the surface of the skin. In the lumbar region of the spine,this distance is approximately 65–75 mm. Consequently, in one embodimentof the invention, the working channel cannula 20 has first portion ofits length somewhat less than the anatomic distance. In one specificembodiment, this length of the first portion is about 66 mm from thedistal end 21 to the mounting bracket 27. In some surgical applications,the mounting bracket 27 may actually rest against the skin of thepatient so that the distal end 21 of the working channel cannula can becloser to the surgical site.

Further in accordance with the present invention, the remaining secondportion of the length of the cannula 20 above the mounting bracket 27 isminimized. In accordance with the invention, this distance must besufficient to permit extension and retraction of the lens 191 relativeto the distal end 21 of the cannula 20. As described above, the travelof the optical lens 191 is preferably 15 mm, so that the remaininglength of the cannula 20 is about 26 mm to accommodate this travel andto provide adequate surface for engagement by the clamping rings 172.Thus, in the preferred embodiment, the working channel cannula 20 has anoverall length of 92 mm. In accordance with one aspect of the invention,it has been found that the relative length between the first portion ofthe cannula disposed within the patient to the second portion of thecannula length situated outside the patient have a ratio of 2:1 to 3:1.In other words, the length of the first portion is between two to threetimes longer than the length of the second portion.

It has also been found that it is desirable to minimize the height ofthe fixture 170 beyond the end of the working channel cannula 20. Inaccordance with the present invention, the optics mounting body 178 hasa height of about 21 mm between the stop edge 179 and the top face ofthe body 178. This distance is not so great that the surgeon hasrestrained from manipulating instruments directly above the fixture 170.Of course, it is preferable that the surgeon manipulate the instrumentsdirectly above the proximal end 22 of the working channel 20 immediatelyadjacent to the fixture 170.

In the present preferred embodiment, the working channel cannula has aninner diameter of about 15 mm and an outer diameter of about 16 mm.Alternatively, the cannula can be provided in a smaller size for otherregions of the spine. In a further specific embodiment, the cannulainner diameter is 12.7 mm with a 14 mm outer diameter. In another aspectof the invention, the overall length and diameter of the working channelcannula 20 is calibrated again relative to the distance L of the spinalanatomy. With the larger diameter working channel, the surgeon canorient certain instruments at an angle relative to the longitudinal axisof the cannula 20. In specific embodiments, this angle is approximately5–6°. It has been found that this angle, together with the large workingchannel 25, gives the surgeon greater flexibility and mobility withinthe surgical site to perform various operations. To that end, the lengthand diameter of the working channel cannula 20 is appropriately sized tomaintain this flexibility, without getting too large. A working channelcannula 20 that has too large a diameter is less adaptable to the spinalanatomy.

In accordance with preferred methods using the devices of the presentinvention, the working space is generally limited to the region directlyadjacent the laminae of a vertebra. A cannula having a diameter that istoo large will interfere with the spinous process when the working spaceis created, and will require resection of greater amounts of tissue thanis preferred for an optimal percutaneous procedure. Therefore, inaccordance with one aspect of the invention, the working channel cannulahas a relationship between its length and its diameter to permit toolangles through the cannula of between 5–8°. In accordance with onespecific aspect of the present invention, the cannula can have a lengthto diameter ratio of between about 5.5:1 to 7:1. Further in accordancewith the present invention, the working channel cannula has a lengththat is no more than 20–30 mm greater than the distance L (FIG. 24)between the laminae and the skin of the patient.

One important feature of the present invention is achieved by the largediameter of the working channel 25 in the cannula 20. This largediameter allows the surgeon or surgeons conducting the surgicalprocedure to introduce a plurality of instruments or tools into theworking space. For example, as described above, a tissue retractor anddiscectomy instruments can be simultaneously extended through theworking channel. In the illustrated embodiment, the discectomyinstruments could include a trephine for boring a hole through the discannulus and a powered tissue cutter for excising the herniated discnucleus. Likewise, the present invention contemplates the simultaneousintroduction of other types of instruments or tools as may be dictatedby the particular surgical procedure to be performed. For example, anappropriately sized curette and a rongeur may be simultaneously extendedthrough the working channel into the working space. Since all operationsbeing conducted in the working space are under direct visualizationthrough the viewing element, the surgeon can readily manipulate each ofthe instruments to perform tissue removal and bone cutting operations,without having to remove one tool and insert the other. In addition,since the surgical procedures can be conducted without the necessity ofirrigation fluid, the surgeon has a clear view through the working spaceof the target tissue. Furthermore, aspects of the invention which permita wide range of motion to the viewing element allow the surgeon toclearly visualize the target tissue and clearly observe the surgicalprocedures being conducted in the working space.

The surgeon can capitalize on the same advantages in conducting a widerange of procedures at a wide range of locations in the human body. Forexample, facetectomies could be conducted through the working channel bysimply orienting the working channel cannula 20 over the particularfacet joints. The insertion of vertebral fixation elements can also beaccomplished through the devices. In this type of procedure, an incisioncan be made in the skin posterior to the location of the vertebra atwhich the fixation element is to be implanted. Implementing the stepsshown in FIG. 10, the cannula 20 can be positioned through the incisionand tissue directly above the particular location on the vertebra to beinstrumented. With the optics extending through the working channel, aninsertion tool holding the vertebral fixation element can be projectedthrough the cannula 20 and manipulated at the vertebra. In one specificembodiment, the fixation element can be a bone screw. The workingchannel 25 has a diameter that is large enough to accept most bonescrews and their associated insertion tools. In many instances, thelocation of the bone screw within the vertebra is critical, soidentification of the position of the cannula 20 over the bony site isnecessary. As mentioned above, this position can be verifiedfluoroscopically or using stereotactic technology.

In many prior procedures, cannulated bone screws are driven into thevertebra along K-wires. The present invention eliminates the need forthe K-wire and for a cannulated screw. The working channel itself caneffectively operate as a positioning guide, once the cannula 20 isproperly oriented with respect to the vertebra. Moreover, the devicesallow insertion of the bone screw into the vertebra to be conductedunder direct vision. The surgeon can then readily verify that the screwis passing into the vertebra properly. This can be particularlyimportant for bone screws being threaded into the pedicle of a vertebra.The working channel cannula 20 can be used to directly insert aself-tapping bone screw into the pedicle, or can accept a variety oftools to prepare a threaded bore within the pedicle to receive a bonescrew.

The devices can also be used to prepare a site for fusion of twoadjacent vertebrae, and for implantation of a fusion device or material.For example, in one surgical technique, an incision can be made in theskin posterior to a particular disc space to be fused. The incision canbe made anteriorly, posteriorly or posterior laterally. If the incisionis made anteriorly for anterior insertion of the working channel, it isanticipated that care will be taken to retract tissues, muscle andorgans that may follow the path of the incision to the disc space.However, the devices of the present invention allow this tissueretraction to occur under direct vision so that the surgeon can easilyand accurately guide the cannula 20 to the disc space without fear ofinjury to the surrounding tissue. As the tissue beneath the skin issuccessively excised or retracted, the working channel cannula 20 can beprogressively advanced toward the anticipated working space adjacent thevertebral disc. Again under direct vision, the disc space can beprepared for implantation of fusion materials or a fusion device.Typically, this preparation includes preparing an opening in the discannulus, and excising all or part of the disc nucleus through thisopening.

In subsequent steps, a bore is cut through the disc annulus and into theendplates of the adjacent vertebrae. A fusion device, such as a bonedowel, a push-in implant or a threaded implant can then be advancedthrough the working channel of the cannula 20 and into the prepared boreat the subject disc space. In some instances, the preparatory stepsinvolve preparing the vertebral endplates by reducing the endplates tobleeding bone. In this instance, some aspiration and irrigation may bebeneficial. All of these procedures can be conducted by tools andinstruments extending through the working channel cannula 20 and underdirect vision from the viewing element.

In some instances, graft material is simply placed within the preparedbore. This graft material can also be passed through the working channelcannula 20 into the disc space location. In other procedures, graftmaterial or bone chips are positioned across posterior aspects of thespine. Again, this procedure can be conducted through the workingchannel cannula particularly given the capability of the cannula to bemoved to different angles from a single incision site in the skin.

The present invention provides instruments and techniques for conductinga variety of surgical procedures. In the illustrated embodiments, theseprocedures are conducted on the spine. However, the same devices andtechniques can be used at other places in the body. For example, anappropriately sized working channel device 10 can be used to removelesions in the brain. The present invention has particular value forpercutaneous procedures where minimal invasion into the patient isdesirable and where accurate manipulation of tools and instruments atthe surgical site is required. While the preferred embodimentsillustrated above concern spinal procedures, the present invention andtechniques can be used throughout the body, such as in the cranialcavity, the pituitary regions, the gastro-intestinal tract, etc. Theability to reposition the viewing optics as required to visualize thesurgical site allows for much greater accuracy and control of thesurgical procedure. The present invention allows the use of but a singleentry into the patient which greatly reduces the risk associated withopen surgery or multiple invasions through the patient's skin.

In accordance with yet another aspect of the present invention, a tissueretractor apparatus 230 is provided that combines a tissue retractor 231with an optical viewing device 232. Referring to FIGS. 25–26, theretractor apparatus 230 includes a retractor plate 234 that is affixedto a grip 235 for manual support of manipulation of the retractor. Thegrip 235 is at the proximal end 236 of the plate. The distal end 237 ofthe retractor plate preferably has a blunt tip 238 to avoid trauma uponinsertion and manipulation of the tissue retractor. Preferably, theblunt tip 238 is angled slightly away from the plate 234. The retractorplate 234 defines an outer retraction surface 239 that can be configuredaccording to the type of surgery being performed. In a preferredembodiment, the plate 234 is semi-cylindrical in configuration to permitatraumatic retraction of tissue adjacent a surgical site. In addition,the retractor plate 234 defines a channel 240 that helps define aworking channel. As thus far described, the retractor 231 issubstantially similar to the retractor 70 depicted in FIGS. 4–6 and asdescribed above.

In accordance with this embodiment of the invention, an optical viewingdevice 232 is supported within the retractor 231 by way of a number ofC-clips 245. Preferably, the C-clips 245 are formed of a resilientmaterial, such as plastic or thin flexible metal, and are affixed to thechannel 240 of the retractor plate 234. In accordance with one specificembodiment, two such C-clips 245 are provided to stably mount theoptical viewing device 232 relative to the retractor 231. Preferably,the clips 245 are sized to support an optical viewing device 232 that isconfigured substantially identical to the viewing device 50 describedabove. In the preferred embodiment, the viewing device 232 has a distaltip 52 with an angled lens 54. In accordance with this embodiment, theC-clips 245 provide a resilient friction fit to the optical viewingdevice 232 while still permitting relative sliding and rotation of theviewing device 232 relative to the retractor 231.

In accordance with the present invention, the tissue retractor apparatus230 can be used in a variety of applications, including non-spinalapplications. For example, this tissue retractor can have application intransnasal and transphenoidal surgeries, and in pituitary procedures. Insurgeries of this type, it is not necessarily desirable to provide aclosed cannula, such as a working channel cannula 20. Moreover, thesmaller working space does not lend itself to the use of a closedcannula which would tend to restrict the space available formanipulation of surgical instruments. Consequently, a tissue retractoror speculum of the type shown in FIGS. 25–26 may be very adequate forsurgeries of this type. In this instance, then the working channel isdefined in part by the patient's body itself, and in part by the tissueretractor. The optical viewing device 232 is supported relative to theretractor to permit the same degrees of motion as are available with thedevice 10 described above.

In another embodiment of the invention and referring to FIG. 27, amodular clamp assembly 300 for supporting viewing optics and/orirrigation/aspiration components is provided with the cannula 20. Thisembodiment is mounted on a cannula 20 having features similar to thosepreviously described, and similar features are referenced by the samenumerals. In accordance with this embodiment, the assembly 300 isprovided with a viewing element 310 and a clamp assembly 350, which areshown most clearly in FIGS. 28, 29, and 30. The viewing element 310includes a viewing portion 312 and an illumination element 314 coupledto a body portion 316. As shown more clearly in FIG. 28, body portion316 has an optics cannula 320 and dovetail 330 extending therefromtowards the cannula 20 when placed thereon. Preferably, dovetail 330 isintegrally formed with the body portion 316. When engaged to the cannula20, optics cannula 320 extends from a proximal end 22 of cannula 20 todistal working end 21, as shown in FIG. 27.

In the embodiment of the present invention, illustrated in FIG. 27 a,the distal working end 21 is beveled and includes a cutting edge 302 forpenetrating bone and soft tissue. A sloped retraction surface 304extends from edge 302 to outer surface 23 of cannula 20. Retractionsurface 304 acts to gradually separate tissue while minimizing damagethereto as the cannula is advanced to the desired depth at the surgicalsite.

Body portion 316 defines an optics bore (not shown) for receiving andsupporting optics cannula 320, and to provide visual communication toviewing portion 312. In one embodiment, the optics bore communicateswith illumination element 314, which is configured to communicate withan illumination source. In a preferred embodiment, components of theviewing portion 312, such as the eyepiece component 326 and focusadjustment knob 327, are integrally formed with the body portion 316. Inan alternate embodiment, the viewing portion 312 is threadingly coupledto body portion 316.

Referring now to the clamp assembly 350, there is included a clamp ring352 and a viewing element receiving portion 390 extending from clampring 352. Receiving portion 390 defines a dovetail receptacle 396 forreceiving an insertion end 332 of dovetail 330 in sliding engagement. Itshould be understood that the receptacle 396 may alternately be definedby body portion 316 of viewing element 310, and dovetail 330 may extendfrom receiving portion 390 to engage the receptacle 396.

Clamp ring 352 substantially encircles an outer surface 23 of cannula20. In particular, clamp ring 352 includes a clamping surface 356 (seeFIG. 28). In a preferred embodiment, clamping surface 356 hassubstantially the same configuration and dimension as outer surface 23of cannula 20. The clamping ring 352 includes clamping arms 354 a and354 b at the free ends of the ring 352. The clamping arms 354 a and 354b define a slot 358 therebetween. As described below in more detail, theslot 358 permits arms 354 a and 354 b to be compressed toward each otherto thereby compress clamping surface 356 of the ring 352 about the outersurface 23 of the cannula. It is understood that when clamping ring 352is loosened, the clamp assembly 350, and if engaged thereto, the viewingelement 310 are free to rotate about the circumference of the cannula 20in the direction of arrow N. Additionally, the clamp assembly 350 cantranslate along the longitudinal length of the cannula 20 in thedirection of the arrow T. The length of travel is limited by the bracket27 used to engage the flexible support arm 160 as described previously.

Extending from and integrally formed with clamp ring 352 is receivingportion 390. In a preferred embodiment, receiving portion 390 includes asurface 392 that abuttingly engages a stop surface 328 of body portion316 when dovetail 330 is fully received within receptacle 396. In oneembodiment, stop surface 328 of the viewing element 310 limits thedownward travel of the assembly 300 along the cannula 20 by engagingproximal end 22 of cannula 20.

In a further aspect of the clamp assembly 350, an irrigation port 393,shown in FIG. 29, can be provided through receiving portion 390 to allowconnection of irrigation cannula 324 to an irrigation tube 225 b viairrigation port 393. Luer® lock fitting 227 b couples tube 225 b to anirrigation source (not shown). An aspiration port 392 may also beprovided through clamp assembly 350 to allow connection of aspirationcannula 322 to an aspiration tube 225 a through aspiration port 392.Luer® lock fitting 227 a couples tube 225 a to an aspiration source (notshown). It should be understood that the clamp assembly 350 may beprovide with both an irrigation cannula 324 and an aspiration cannula322 with corresponding ports 393 and 392 through receiving portion 390.In one embodiment, only one of the irrigation/aspiration cannulas andits corresponding port is provided. In another embodiment, no irrigationor aspiration cannulas or ports are provided. In yet another embodiment,a single irrigation/aspiration cannula and port is provided andirrigation and aspiration is performed alternately through the singletube and port. It should be understood that the irrigation/aspirationcannula(s) may be used according to the methods described above.

Clamp assembly 350 and viewing element 310 are releasably engaged viaconnection assembly 318. Connection assembly 318 is shown to bepreferably positioned on clamp assembly 350; however, it should beunderstood that in alternate embodiments connection assembly 318 may beprovided on viewing element 310. Referring now to FIG. 31, connectionassembly 318 includes a clip 340 pivotably mounted to viewing elementreceiving portion 390 of clamp assembly 350 via resilient hinges 345. Inthe illustrated embodiment, clip 340 is mounted via two resilient hinges345. In an alternate embodiment, only one hinge 345 is used to mountclip 340.

Resilient hinge 345 biases clip 340 to a position, as shown in FIG. 31,where the body of clip 340 is substantially parallel to body portion 316and receiving portion 390. A protuberance 335 projects from and ispreferably integrally formed with body portion 316 of viewing element310. Clip 340 defines an aperture 342, 343 configured and positioned toreceive protuberance 335 when dovetail 330 is fully received withinreceptacle 396, placing the viewing element 310 and the clamp assembly350 in an assembled position (as shown in FIG. 27.) In the assembledposition, stop surface 328 is proximate engagement surface 392. In oneembodiment, stop surface 328 engages engagement surface 392. In anotherembodiment, a space is left between stop surface 328 and engagementsurface 392 when the viewing element 310 is coupled to clamp assembly350.

Clip 340 has a first end 346 defining a nose portion 344 extendingtoward viewing element 310 when it and clamp assembly 350 are positionedas shown in FIG. 28. Protuberance 335 defines an inclined surface 336that opposes nose portion 344. Nose portion 344 slidingly engages theinclined surface 336 as dovetail 330 is placed in receptacle 396. Thisprotuberance acts as a cam to rotate the nose portion 344 as it movesalong inclined surface 336, causing the clip 340 to rotate in adirection indicated by arrow P. As the dovetail 330 is furtherpositioned within receptacle 396, the wall 343 of aperture 342, 343eventually communicates with engagement surface 337 of protuberance 335.Hinge 345 then biases the clip 340 to the position shown in FIG. 31,where the engagement surface 337 engages an endwall 343 that defines aportion of the aperture 342, 343.

Once coupled the viewing element 310 and clamp assembly 350 areeffectively held in such position by the clip 340. In order to uncouplethe scope/clamp assembly, clip 340 is rotated by depressing second end347 via handle portion 341 in the direction of arrow “P” to rotate theclip 340 about hinge 345. Nose portion 344 is thus rotated in thedirection opposite arrow P until endwall 343 no longer engagesengagement surface 337. The viewing element 310 may then be removed fromthe clamp assembly 350 by sliding dovetail 330 out of the receptacle396.

It should be understood that the present invention contemplates otherstructures for coupling viewing element 310 to clamp assembly 350. Forexample (by way of illustration and not limitation), dovetail 330 may bereplaced by one or more guide pins extending from viewing element 330 tobe received within corresponding slots on receiving portion 390.Alternatively, the clip 340 may be provided on one or both of the sideportions of the receiving portion 390.

With reference now to FIG. 32, there is illustrated a plan view of clampassembly 350 and a portion of a section through viewing element 310.Clamp assembly 350 is shown removed from cannula 20 for clarity.Dovetail 330 is shown positioned within receptacle 396, and protuberance335 is received within the aperture 342, 343 of clip 340. Receivingportion 390 further defines an optics recess 359 for receiving opticscannula 320 between irrigation port 393 and aspiration port 394. Opticsrecess 359 allows placement of the optics cannula 320 adjacent theworking channel 25 of the cannula 20.

The clamp assembly 350 may be loosened and rotated or translated aboutthe cannula 20 via the lever arm assembly 360, shown in exploded view inFIG. 32. Lever arm assembly 360 includes fastener 380 coupling a leverarm 366 to clamping arms 354 a and 354 b. Fastener 380 includes anenlarged head 381, a shank portion 382 integrally formed therewith andextending therefrom. Shank portion 382 defines a threaded portion 383remote from the head 381.

Lever arm 366 has a first end 369 and a second end 371. In proximatesecond end 371 there is a portion of a bearing bore through lever arm366 which has a shank receiving portion 372 and a colinear headreceiving portion 375. Lever arm 366 also includes an inside face 367adjacent arm 354 b. Projecting from face 367 and integrally formedtherewith is cam portion 364. Referring to FIG. 33, cam portion 364 hasone or more arcuate inclined ramps 377 a, 377 b, 377 c, 377 d,collectively designated as ramps 377. Each ramp 377 is inclined upwardfrom a low portion 378 to a high portion 379. Between low portions 378and high portions 379 of adjacent ramps 377 are detents 374.

Referring back to FIG. 32, clamping arms 354 a and 354 b have a bore 361which includes a threaded portion 368 in arm 354 a, and the otherportion of the bearing bore having a bearing portion 370 and a colinearshank receiving portion 372 in arm 354 b. Arm 354 b also includesprojections 362 a and 362 b extending therefrom and integrally formedtherewith. Projections 362 a and 362 b are configured to releasablyengage and be received within a corresponding one of the detents 374.

When lever arm assembly 360 is assembled, threaded portion 383 offastener 380 threadingly engages clamp arm 354 a to secure lever arm 366thereto. Shank portion 382 is rotatably received within shank receivingportions 372, and head 381 is received within head receiving portion375. By rotating lever arm 366 about shank 382 of fastener 380, leverarm 366 is operable to selectively compress or release arms 354 a and354 b to allow clamping surface 356 to engage outer surface 23 ofcannula 20. Thus rotation of the assembly 300 is accomplished in the Ndirection or translation in the T direction (FIG. 27) along cannula 20by releasing clamping ring 352. In order to release clamp ring 352,lever arm 366 is positioned so that projections 362 releasably engage acorresponding one of detents 374 adjacent low portions 378. It isunderstood that the detents 374 are configured to allow disengagement ofprojections 362 by a reasonable force applied to first end 369 of leverarm 366. Once clamp ring 352 is in the desired position, the lever arm366 is rotated so that the projections slide up corresponding ones ofthe ramps 377 until the projection falls into a detent between the highportions 379 of adjacent ramps 377, thus compressing and then holdingclamp ring 352 about the outer surface 23 of the cannula 20.

FIG. 34 illustrates an alternate configuration cam 364′ of lever arm366. In this embodiment, there is provided two ramps 377 a and 377 b.Adjacent high portions 379 a, 379 b of each ramp 377 a, 377 b is acorresponding detent 374 a, 374 b, respectively. Stops 386 a and 386 bare provided adjacent a corresponding one of the detents 374 a, 374 bopposite the high portions 379 a, 379 b. A first side 387 a, 387 b ofstops 386 a, 386 b is configured to prevent detents 374 a, 374 b frombeing rotated past projections 362 when clamp 352 is clamped to thecannula 20. When the lever arm 366 is manipulated to release projections362 from the detents 374 a, 374 b in order to release clamp 352, theprojections slide down ramps 377 a, 377 b to inside face 367. A backside 388 a, 388 b of stops 386 a, 386 b engage the projections to limitfurther rotation of the lever arm 366.

In the embodiment of FIG. 33, the detents 374 are spaced at 90 degreesabout the cam 364. Thus, the lever arm 366 moves through an angle ofabout 90 degrees to move the projections 362 from a detent 374 adjacentto a lower portion of the ramp to a detent 374 adjacent an upper portionof the ramp. In the embodiment of FIG. 34, the detents 374 are spaced at180 degrees, but the inclined ramps 377 a and 377 b terminate uponturning through an arc of about 90 degrees. Preferably, when clamp ring352 is engaged to cannula 20, lever arm 366 extends perpendicular tocannula 20 and is positioned adjacent the clamp ring 352, as illustratedin FIG. 32. This minimizes the profile of clamp assembly 350 and anyinterference that could be caused by lever arm 366 with the surgeon'smanipulation of tools and performance of surgical procedures. In oneembodiment, the lever arm is rotated 90 degrees to be parallel to thecannula in order to release clamp 352 to reposition or remove the clampassembly 350. In another embodiment, the clamp 352 is released when thelever arm 366 is rotated in the range of about 45 degrees to about 135degrees from its clamped position perpendicular to the axis of thecannula 20.

Referring now to FIG. 35, another embodiment of a clamping assembly ofthe present invention is illustrated and designated at 400. Clampingassembly 400 has a ring that includes a pair of clamping arms 402 and404. Arms 402 and 404 are pivotably coupled with one another viaclamping mechanism 401. Clamping mechanism 401 includes a pair of lever408 and 410 coupled to hinge portion 406. Levers 408 and 410 and hinge406 are coupled to arms 402 and 404, and allowing the arms 402, 404 tobe selectively engaged to the outer surface 23 of cannula 20. Clampmechanism 400 further includes a viewing element receiving portion 412extending from and integrally formed with one the clamping arms (shownin FIG. 35 connected to arm 402). Receiving portion 412 is similarlyconfigured to function like viewing element receiving portion 390, asillustrated and described with respect to FIGS. 28–29, with likeelements being indicated by like reference numerals. Lever arm 402defines a cannula engaging surface 416, and lever arm 404 defines acannula engaging surface 418. Free end 403 of lever arm 492 and free end405 of lever arm 404 define a slot or gap 419 therebetween. The size ofgap 419 is not critical, so long as arms 402, 404 are operable toselectively grip the cannula 20.

Arms 402 and 404 are biased by a spring (not shown) coupled to hinge 406so that clamping surfaces 416, 418 provide a gripping force againstouter surface 23 of cannula 20. In order to rotate, translate, or removethe clamping mechanism with respect to the cannula 20, lever arms 408,410 are pressed towards one another (as indicated by the arrows 408 a,410 a in FIG. 35) to separate first ends 403 and 405. The grip ofclamping surfaces 416, 418 is then released from outer surface 23, andthe mechanism 400 may be moved along the length of the cannula 20 orremoved from the cannula 20 according to the need of the surgeon.

It is contemplated that hinge 406 may be any type of hinge suitable forclamping clamp mechanism 400 to cannula 20 as would occur to thoseskilled in the art. For example, hinge 406 may includes a pin extendingthrough colinear bores defined by the clamping arms 402, 404, with aspring biasing arms 402, 404 to their clamping position.

It should be understoood that clamp assemblies 350 and 400 each allowrotation and translation of optics 190 similarly as described above withrespect to fixture 170.

In accordance with one specific embodiment of the invention, portions ofviewing element 310 and the components of the clamp assemblies 350 and400 are formed of a flexible and resilient material. For example, thebody portion 316 and receiving portion 390 can be formed of a plastic,such as polycarbonate, and are particularly well-suited to typicalplastic molding techniques. Likewise, the lever arm 366 and can bemolded from a plastic material. In one specific embodiment, thesecomponents are formed of Delrin®, since Delrin® provides a smoothsurface for the relative movement between the projections 362 on theclamping arm 354 b and the cam faces 364, 364′ of lever arm 366.

It is understood that the travel of the barrel clamping mechanism 360and biasing force of mechanism 401 can be calibrated so as to tightlycompress the clamping ring 352 and arms 402, 404 respectively, about thecannula 20. It is also understood that this compression must not be sogreat as to compromise the integrity or strength of the cannula 20. Inone specific embodiment, the slot 358 is larger than the maximum travelof the barrel clamp mechanism 360 along inclined ramps 377 so that theprojections 362 can rest solidly within the detents 374 of the lever arm366. In accordance with one specific embodiment, the slot 358 has adimension of 2.0 mm while the throw of the barrel clamp mechanism 360achieved by the cam 364 is 1.0 mm.

From the foregoing description of the embodiments of the presentinvention illustrated in FIGS. 27–36, several advantages and methods ofusing the present invention should be understood. The detachability ofthe viewing element 310 from the clamp assemblies 350 or 400 allowsmultiple uses of a single viewing element 310. The same viewing element310 may also be used with clamp assemblies manufactured for differentsized and shaped cannulas. Since a single viewing element 310 may beused for multiple sized cannulas and clamp assemblies, the unit cost perprocedure is reduced. Also, it is cost-effective to manufacture theviewing element and its components from high-quality materials. Forexample, optics cannula 320 may be made from stainless steel. Highquality materials for optical components often enable the use ofsmaller-sized components, thus conserving additional area in the workingchannel of the cannula for surgical working space. In one specificembodiment, optics cannula 320 has a diameter of about 3 mm. Optimumpicture quality may also be obtained by use of glass components in theviewing element.

Referring now to FIGS. 36–37, alternate embodiments of cross-sectionsfor the cannula 20 are illustrated. The cannula 20 has been illustratedwith having a generally circular cross-section. It is also contemplatedthat the cannula 20 have non-circular cross-sections. For example, FIG.36 cannula 430 has an outer surface 432 that defines an ovalcross-section. In FIG. 37, the cannula 440 has an outer surface 442 thatdefines a square cross-section. Of course, it should be understood thatcorresponding adjustments in the design and configuration of thefixtures and clamping assemblies described herein are also required inorder to engage the outer surface of the cannulas illustrated in FIGS.36–37. In one embodiment, the cannula 20 of the present invention has avariable cross section profile along at least a portion of its lengthbetween proximal end 22 and distal end 21. The variable profile providesa larger cross-sectional dimension and/or area at the proximal end 22than at the distal working end 21. In one form, the variable profiledefines a frusto-conical portion along longitudinal axis L of thecannula 20.

Referring now to FIGS. 38–48, a device 500 for performing percutaneoussurgery is provided according to another embodiment of the presentinvention. As shown in FIG. 38, device 500 includes a clamp assembly 550for supporting a viewing element 510 on a tubular retractor or cannula501. Though not illustrated in FIG. 38, viewing element 510 can beprovided with or without irrigation/aspiration components as discussedabove with respect to device 300. Clamp assembly 550 is engaged on aproximal end 505 of cannula 501, and can preferably be easily removedfrom cannula 501 or moved about cannula 501 by the surgeon duringsurgery to reposition viewing element 510 relative to cannula 501. Sinceclamp assembly 550 is mounted on the proximal end of cannula 501,cannula 501 can have a length sized to position proximal end 505 at orjust slightly above skin level S, as shown in FIG. 39, when distal end504 is at the desired location in the patient.

As further shown in FIG. 39, cannula 501 has a working channel 502 thatextends between a distal end 504 and proximal end 505. Cannula 501 canhave any cross-sectional shape as discussed above, including oval,elliptical, or circular cross-sectional shapes, for example. Distal end504 can be beveled to facilitate percutaneous insertion of cannula 501as discussed above with respect to cannula 20. A ring 506 is providedaround the proximal end 505 of cannula 501 to enlarge proximal end 505.Preferably, ring 506 has an outer diameter that is slightly larger thanthe diameter at outer surface 503 of cannula 501 such that a lower lip507 is formed around outer surface 503 by ring 506. A bracket 527extends outwardly from proximal end 505 and is provided for attachmentof a flexible arm thereto to secure cannula 501 to a surgical table suchas discussed above.

Referring back to FIG. 38, viewing element 510 includes a viewing port512 and an illumination element 514 coupled to a body portion 516.Viewing element 510 further includes an optics cannula 520 as discussedabove with respect to optics cannula 190 and 320. Body portion 516defines an optics bore (not shown) for receiving and supporting opticscannula 520, and to provide visual communication between optics cannula520 and viewing portion 512. The components of viewing portion 512 caninclude an eyepiece component and focus adjustment knob, which can beintegrally formed with the body portion 516 or threadingly coupledthereto.

With viewing element 510 supported by clamp assembly 550, and clampassembly 550 engaged to cannula 501, optics cannula 520 extends frombody portion 516 and at least partially into working channel 502 ofcannula 501. As will be discussed further below, clamp assembly 550 canbe moved about cannula 501, and can also be engaged/disengaged fromcannula 501 when cannula 501 is positioned in the patient. A microscope525, as shown in FIG. 39, can be positioned over working channel 502 inorder to view the working space at the distal end of cannula 501 alongviewing axis 526. Preferably, clamp assembly 550 and viewing element 510are removed when using microscope 525 to increase the field of view andprovide additional room for surgical instruments to be used throughcannula 501. The present invention gives the surgeon flexibility inselecting the desired viewing system, whether it be endoscopic ormicroscopic, and to efficiently alternate between viewing systems duringthe surgical procedure.

In one specific embodiment, it is contemplated that cannula 501 can beprovided in lengths ranging from 30 millimeters to 90 millimeters,preferably in increments of 10 millimeters. It is contemplated thatcannula 501 can have a diameter of 14, 16, 18 or 20 millimeters. Itshould be understood, however, that the present invention contemplatesthat cannula 501 can have other lengths and diameters. The appropriatelength for cannula 501 will depend on the depth of the desired locationfor distal end 504 below the skin S of the patient in order to completethe surgical procedure, the anatomical location of the surgery, and thepatient's anatomy. These factors in cannula selection can be evaluatedthrough pre-operative planning prior to surgery by x-rays or other knowimaging technique, and can be adjusted during the surgical procedure ifnecessary since cannulas of differing lengths and diameters can be madeavailable.

Referring now to FIGS. 40 through 48, further details of clamp assembly550 will now be described. Clamp assembly 550 includes a generallyvertical viewing element mounting portion 552 and a foot 554 extendingtherefrom and oriented generally orthogonally therewith. Foot 554 has achannel 560 sized to receive ring 506 of cannula 501 when foot 554 isplaced over proximal end 505 of cannula 501. Preferably channel 560 hasa curved inner lip 562 positionable along the inside surface of cannula501 and a curved outer lip 563 positionable along the outer surface ofring 506. Inner lip 562 preferably has a concave profile to match theprofile of the inner surface of cannula 501 to minimize its protrusioninto working channel 502. It is further contemplated that the radius ofcurvature of one or both inner lip 562 and outer lip 563 cansubstantially differ from the radius of curvature of the adjacentcannula wall surface so that channel 560 of the same clamp assembly 550can be used with cannulas of differing diameters. For example, inner lip562 can have a radius of curvature that corresponds approximately to theradius of curvature of the inner surface of a first cannula that has acannula diameter of 14 millimeters. Outer lip 563 can have a radius ofcurvature sized to approximately correspond to the radius of curvatureof ring 506 of a second cannula that has a cannula diameter of 18millimeters. This allows the same clamp assembly 550 to be used forcannulas having diameters in the range of 14 millimeters to 18millimeters.

Foot 554 has a lever arm 556 pivotally engaged thereto via fastener 558.Lever arm 556 has a handle 566 and a cam or clamping member 564integrally formed with and extending from handle 566. As further shownin FIGS. 44 and 45, clamping member 564 has a cam or clamping surface568 positionable against outer surface 503 of cannula 501 when foot 554is placed on ring 506 of cannula 501. Clamping member 564 includes athreaded hole 574 extending therethrough engaged by fastener 558. Asshown in FIG. 46, fastener 558 has a head 579 with a tool engagingrecess, a non-threaded portion 580 adjacent head 579, and a distalthreaded portion 582. Non-threaded portion 580 extends through and isfreely rotatable in foot 554, while threaded portion 582 pivotablyattaches lever arm 556 to foot 554.

Lever arm 556 includes an offset 578 that positions clamping member 564below foot 554 while allowing handle 566 to extend alongside foot 554and mounting portion 552 when lever arm 556 is in its engaged position(FIG. 40.) Offset 578 further enables lever arm 556 to be rotated in thedirection of arrow 570 a sufficient distance and positioned alongsidecannula 501 so that there is no interference or contact between clampingmember 564 and lip 507, facilitating removal of clamping assembly 550from cannula 501. Clamping member 564 further has an angled lead-in inthe form of ramped surface 576 formed on upper surface 575. Rampedsurface 576 facilitates passage of clamping member 564 below ring 506until upper surface 575 contacts lip 507 to engage clamp assembly 550 toring 506.

To secure clamp assembly 550 to cannula 501, channel 560 is positionedon ring 506 with inner lip 562 positioned along the inner surface ofcannula 501 and outer lip 563 positioned along the outer surface of ring506. Channel 560 preferably has a depth sufficient to accommodate theheight of ring 506 so that upper surface 575 of lever arm 556 ispositioned below ring 506. When lever arm 556 is in the engaged positionshown in FIG. 40, clamping surface 568 contacts outer surface 503 ofcannula 501 and upper surface 575 contacts lip 507. Frictionalengagement between outer surface 503 and the engagement with ring 506secures clamp assembly 550 to cannula 501. In this engaged positioned,handle 566 is positioned adjacent to foot 554, with foot 554 limitingthe range of movement of lever arm 556 in the direction opposite arrow570. It is understood that the dimensional relationship between foot554, lever arm 556 and cannula 501 can be established so clampingassembly 550 can be immovably engaged to cannula 501. It is alsounderstood that compression forces applied by clamp assembly 550 are notso great as to compromise the integrity or strength of cannula 501.

To disengage clamp assembly 550 from cannula 501, lever arm 556 is movedin the direction of arrow 570 until clamping surface 568 no longercontacts outer surface 503 and clamping member 564 is no longer belowlip 507, allowing clamp assembly 550 to be lifted off of cannula 501. Astop member 572 extending downwardly from foot 554 limits rotation oflever arm 556 in the direction of arrow 570. Lever arm 556 can also berotated in the direction of arrow 570 to disengage clamping surface 568from cannula 501 without removal of clamp assembly 550 from cannula 501.This allows viewing element 510 to be rotated about the perimeter of theproximal end of cannula 501 in the directions indicated by arrow N ofFIG. 38 in order to position the lens at the desired location in workingchannel 502 with respect to the surgical site.

Additionally, viewing element 510 can be translated along the length ofthe viewing element mounting portion 552 in the direction of the arrow Tin order to position the lens at the desired location with respect todistal end 504 and the surgical site. Viewing element mounting portion552 includes an elongated body 583 extending between a top end 585 and abottom end 587. Body 583 is integrally formed with or fixedly attachedto foot 554 at bottom end 587 and extends upwardly therefrom to a topend 585. The length of travel of viewing element 510 in the direction ofarrow T along mounting portion 552 is limited by height H (FIG. 40.) Inone specific embodiment, height H is in the range of 69 to 73millimeters. It is further contemplated that other embodiments can haveheights greater than 73 millimeters or less than 69 millimeters.Preferably, height H is sufficient to position body portion 516 awayfrom the proximal end opening of cannula 501 to provide room for theinsertion and manipulation of surgical instruments in working channel502.

Body 583 includes a first side surface 586 and an opposite second sidesurface 588. A number of V-shaped grooves 584 are formed in body 583along first side surface 586 and along height H. Mounting portion 552further includes a first track 590 along a first end surface 591 and asecond track 592 along a second end surface 593. First and second tracks590, 592 have a V-shape in the illustrated embodiment; however othershapes are also contemplated. A notch 594 is formed in body 583 at topend 585.

Viewing element 510 is mounted to clamp assembly 550 by a bracketassembly 600 and a roller 650. Bracket assembly 600 includes a U-shapedconnector 602 positionable around viewing element mounting portion 552,and a viewing element support member 604 extending from connector 602.Connector 602 further includes an end wall 610 extending between a firstarm 606 and a second arm 608. First arm 606 includes a first hole 607formed therethrough, and second arm 608 includes a second hole 609formed therethrough. Body portion 583 is positioned between arms 606,608 and adjacent end wall 610, and roller 650 is rotatably mounted inholes 607, 609 and in contact with grooves 584 along first side surface586. Connector 602 has a first nub 624 extending from first arm 606 thatis preferably V-shaped and positionable in first track 590. Connector602 also includes a second nub 626 extending from second arm 608 that isalso preferably V-shaped and positionable in second track 592. Nubs 624,626 maintains alignment of connector 602 with body 583 as it is movedtherealong.

In order to maintain firm contact between roller 650 and grooves 584,connector 602 includes a biasing member 614 that keeps body 583 in firmcontact with roller 650. As shown in FIG. 43, biasing member 614 isformed at a reduced thickness portion 612 in endwall 610. Biasing member614 is connected to end wall 610 only along the bottom U-shaped portion,and its upper ends 614 a and 614 b are not connected with end wall 610.Ends 614 a, 614 b can be bent or pushed away from end wall 610 to applya biasing force against second side 588 of body 583 to keep roller 650engaged in grooves 684 and to prevent bracket assembly 600 fromfree-falling along body 583. Other forms for biasing member 614 are alsocontemplated, such as a spring biased plunger. Notch 594 provided at thetop end of body 583 to facilitate assembly of bracket assembly 600 toviewing element mounting portion 552. Notch 594 receives biasing member614 to allow roller 650 to engage in one of the upper-most grooves 584before biasing member 614 contacts body 583 when bracket assembly 600 istop-loaded onto body 583.

As shown in FIGS. 47 and 48, roller 650 includes a thumb paddle 652 anda wheel 654. Roller 650 is rotatably mounted in the holes 607, 609formed in the arms 606, 608, respectively, of connector 602. Wheel 654includes a number of teeth 656 that are V-shaped to fit in the V-shapedgrooves 584 formed along body 583 of viewing element mounting portion552. Teeth 656 engage respective ones of the grooves 584 as roller 650is rotated by hand via thumb paddle 652 to move bracket assembly 600 andthus viewing element 510 in the directions of arrow T along mountingportion 552.

Viewing element support member 604 includes an illumination element slot616 angled therethrough to receive the correspondingly angledillumination element 514. Support member 604 further includes a hole 618for receiving a fastener (not shown) engageable to a hole (not shown) inbody portion 516 of viewing element 510, securing viewing element 510 tosupport member 604. Support member 604 further includes a support ledge620 extending along a bottom portion thereof. A pin 622 extends upwardlyfrom ledge 620. Viewing element 510 includes a hole (not shown)positionable on pin 622 to resist lateral movement of viewing element510 with respect to support member 604 while support ledge helps supportthe weight of viewing element 510.

In accordance with one specific embodiment of the invention, thecomponents of the clamp assembly 550 are made from stainless steel usingfabrication techniques known in the art. In another form, it iscontemplated that the components of clamp assembly 550 can be formedfrom plastic material using fabrication techniques known in the art.

Referring now to FIGS. 49 and 50, another embodiment of the device 500is show is shown that includes a viewing element holder 700 mounted onfoot 554 of clamp assembly 550. Viewing element holder 700 includes aneyelet 702 and a hook member 704 extending therefrom. Hook member 704has an arcuate inner surface 706 extending along an inner side thereofand a side opening 708 sized to receive optics cannula 520. Fastener 558extends through eyelet 702 to couple viewing element holder 700 to foot554 and lever arm 556. Viewing element holder 700 can be keyed orotherwise interconnected with lever arm 556 to move therewith. Whenlever arm 556 is in its engaged position as shown in FIG. 49, hookmember 704 extends around optics cannula 520 with arcuate surface 706 incontact with optics cannula 520. When lever arm 556 is moved to itsunengaged position and pivoted around fastener 558 in the direction ofarrow 570, viewing element holder 700 also pivots around fastener 558 inthe direction of arrow 710 to displace hook member 704 from aroundoptics cannula 520. Viewing element holder 700 can be moved to itsdisengaged position to facilitate assembly and disassembly of viewingelement 510 from clamp assembly 550.

When in its engaged position, viewing element holder 700 resists lateralmovement of optics cannula 520 and maintains its position along theinner sidewall of cannula 501 when optics cannula 520 is contacted by,for example, a surgical instrument. Such movement could interfere withthe surgeon's viewing of the surgical site through the viewing element510. It is preferred that the holding force exerted by hook member 704is not so great as to prevent extension and retraction of viewingelement 510 with roller 650 when viewing element holder 700 is in itsengaged position.

From the foregoing description of the embodiments of the presentinvention illustrated in FIGS. 38–50, several advantages and methods ofusing the present invention should be understood. The detachability ofthe viewing element 510 and clamp assembly 550 allows cannula 501 to beused by the surgeon with a microscope or an endoscope. For example,according to one preferred technique of the present invention, amicroscope can be used during sequential dilation of the tissue andinsertion of cannula 501 to provide working channel access to thesurgical site. A microscope can continued to be used for visualizationwhile instruments are inserted through cannula 501 to perform surgicalprocedures in the working space at the distal end of cannula 501.However, viewing with the microscope can be obstructed by one or moreinstruments that are inserted into the working channel of cannula 501,or when viewing deep within the patient's body is desired. An endoscopicviewing element, such as viewing element 510, can be mounted to cannula501 with clamp assembly 550. Viewing obstructions are then eliminated orminimized since viewing element 510 has optics cannula 520 that placesthe viewing lens adjacent the surgical site. Viewing of the surgicalsite can be further enhanced by the rotational and translationalpositioning capability of the endoscope provided by clamp assembly 550.

Further advantages are realized since the same clamp assembly 550 andviewing element 510 may be used with cannulas of differing diameters.Since a single viewing element 510 may be used for multiple sizedcannulas, the unit cost per procedure is reduced. Also, it iscost-effective to manufacture the viewing element and its componentsfrom high-quality materials. For example, optics cannula 520 may be madefrom stainless steel. High quality materials for optical componentsoften enable the use of smaller-sized components, thus conservingadditional area in the working channel of the cannula for surgicalworking space. In one specific embodiment, optics cannula 520 has adiameter of about 5 millimeters. Optimum picture quality may also beobtained by use of glass components in the viewing element.

Additional advantages are realized since cannula 501 need not extendbeyond the skin level of the patient in order to engage clamp assembly550 thereto. The shorter length cannula allows greater angulation ofinstruments that are inserted through the working channel, reducing thediameter required for the cannula and/or increasing the reach of theinstruments into the working space beyond the walls of the cannula atits distal end.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly the preferred embodiment has been shown and described and that allchanges and modifications that come within the spirit of the inventionare desired to be protected.

1. A device for use in spinal surgery, comprising: a cannula sized forintroduction into a patient, said cannula defining a working channelextending between a distal end and an opposite proximal end, saidcannula further defining a length between said distal end and saidproximal end, said proximal end including a ring extending radiallyoutwardly therefrom about a perimeter of said cannula and forming a lipabout an outer surface of said cannula; a clamp assembly including aviewing element mounting portion extending proximally from said cannula,said clamp assembly further comprising a foot with a channel to receivesaid ring when said clamp assembly is engaged to said cannula, said footoccupying a first portion of the perimeter of said cannula with theremaining portion of the perimeter unoccupied by said foot; and aviewing element engageable to said viewing element mounting portion. 2.The device of claim 1, wherein said clamp assembly contacts an innersurface and an outer surface of said cannula when engaged thereto. 3.The device of claim 1, wherein said perimeter is circular.
 4. The deviceof claim 3, wherein said foot includes an inner lip positionable alongan inner surface of said cannula and an outer lip positionable along anouter surface of said ring.
 5. The device of claim 4, wherein said innerlip includes a concave profile along a concave profile of said innersurface of said cannula.
 6. The device of claim 1, wherein said clampassembly includes a lever arm pivotally coupled to said foot.
 7. Thedevice of claim 6, wherein said lever arm includes a handle and aclamping member, said clamping member including a clamping surfacepositionable against said outer surface of said cannula to secure saidfoot about said ring.
 8. The device of claim 7, wherein said ring ispositioned between said foot and said lever arm when said clampingsurface is positioned against said outer surface of said cannula.
 9. Thedevice of claim 8, wherein said clamping member includes a rampedsurface oriented toward said ring structured to facilitate passage ofsaid clamping member below said ring.
 10. The device of claim 9, whereinsaid clamping member includes an upper surface adjacent said rampedsurface positionable against a lower surface of said lip when saidclamping surface is positioned against said outer surface of saidcannula.
 11. The device of claim 7, wherein said foot includes an innerlip positionable along an inner surface of said cannula, said inner lipclamping against said inner surface when said clamping surface ispositioned against said outer surface of said cannula.
 12. The device ofclaim 1, wherein said viewing element includes an optics cannulapositionable in said working channel of said cannula when said viewingelement is engaged to said viewing element mounting portion.
 13. Thedevice of claim 1, wherein said ring is engageable to a flexible arm tosecure a position of said cannula during spinal surgery.
 14. The deviceof claim 13, wherein said ring includes a bracket extending therefromfor engagement with the flexible arm.
 15. The device of claim 1, whereinsaid viewing element is adjustably positionable along a length of saidviewing element mounting portion to reposition a distal end of saidviewing element relative to said distal end of said cannula.
 16. Adevice for use in spinal surgery, comprising: a cannula sized forintroduction into a patient, said cannula defining a working channelextending between a distal end and an opposite proximal end, saidcannula further defining a first length between said distal end and saidproximal end; a viewing element including an optics cannula extendinginto said working channel; and a clamp assembly including a viewingelement mounting portion extending proximally from said cannula, saidviewing element being mountable to said mounting portion, wherein saidclamp assembly is engageable at a plurality of locations about saidproximal end of said cannula to reposition said optics cannula in saidworking channel and said clamp assembly contacts an inner surface and anouter surface of said cannula when engaged thereto.
 17. The device ofclaim 16, wherein said clamp assembly further comprises a foot with achannel to receive a ring extending radially outwardly about saidproximal end of said cannula.
 18. The device of claim 17, wherein saidring is engageable to a flexible arm to secure a position of saidcannula during spinal surgery.
 19. The device of claim 17, wherein whensaid clamp assembly is engaged to said cannula, said foot occupies afirst portion of the perimeter of said cannula with the remainingportion of the perimeter unoccupied by said foot.
 20. The device ofclaim 16, wherein said viewing element is adjustably positionable alonga length of said viewing element mounting portion to reposition a distalend of said optics cannula relative to said distal end of said cannula.21. The device of claim 16, wherein said perimeter is circular.
 22. Adevice for use in spinal surgery on a patient, comprising: a cannulasized for introduction into a patient, said cannula defining a workingchannel extending between a distal end and an opposite proximal end,said cannula further defining a length between said distal end and saidproximal end and a perimeter extending around said working channel; anda viewing element engageable at a first location along said perimeterwith a clamp assembly and said clamp assembly and said viewing elementare movable about said perimeter for engagement at a second locationabout said perimeter remote from said first location, wherein said clampassembly is configured to occupy a portion of said perimeter whenengaged to said cannula with a remaining portion of said perimeterunoccupied by said clamp assembly.
 23. The device of claim 22, furthercomprising a flexible arm removably coupled to a proximal end ringextending about said proximal end of said cannula, said flexible armmaintaining an orientation of said cannula in the patient.
 24. Thedevice of claim 22, wherein said cannula includes a bracket extendinglaterally from said ring, said flexible arm being engageable with saidbracket.
 25. The device of claim 22, further comprising: said clampassembly including a viewing element mounting portion extendingproximally from said cannula, said clamp assembly further comprising afoot with a channel to receive said proximal end of said cannula whensaid clamp assembly is engaged to said cannula, said foot extendingabout a first portion of the perimeter of said cannula with theremaining portion of the perimeter remaining substantially unobstructed;and said viewing element includes an optics cannula mountable to saidviewing element mounting portion with said optics cannula extending intosaid working channel.
 26. The device of claim 25, wherein said clampassembly is engageable to an inner surface and an outer surface of saidcannula.